GURPS Space by anagramarye

1 no, not any aliens yet
2 oh god, the physics
3 look at all those details
4 finally, some Goddamned aliens up in here
5 Nitrogencrabwhalebird
5.1 An example alien (Garden-type planet)
5.2 An example alien (Silicon-type planet)

no, not any aliens yet

posted by anagramarye Original SA post

GURPS Space, Part I—or—no, not any aliens yet

GURPS Space is a hell of a book. Like space opera? Like hard sci-fi? It's got everything for you. I mean everything—entire chapters about campaign types, genre guidelines, and plot hooks. If you like mechanics, though, the real gem of the book is in three chapters in particular: "Basic Worldbuilding", "Advanced Worldbuilding", and "Alien Life and Alien Minds". With them, you can generate a planet, a star system, and a unique alien species from scratch, all through random dice rolling, and it works . This isn't some space opera game like Traveller... this is detailed stuff based on actual physics, astronomy, and biology.

I'm going to be making an alien species with this, but I'm going to start from scratch with a planet and randomly roll all the way through.

The first 3d6 roll (there's going to be a lot of them) comes up as a 6. This indicates a Hostile World . Rolling on the subtable (another 3d6) results in a Standard (Ammonia) world.

GURPS Space, Ammonia Chemistry posted:

This world type world is large enough to retain a thick atmosphere, along with plenty of water and other light volatile compounds. However, it is so cold that pure water would be eternally frozen and Earthlike life could not possibly survive. Instead, the atmosphere is primarily composed of ammonia and methane, and the oceans are composed of liquid ammonia mixed with a substantial amount of water. Ammonia-based life is possible on such a world. Ammonia worlds are very unlikely except near cool red dwarf stars; the compound breaks down quickly when exposed to the ultraviolet light given off by brighter stars like our own sun. There are no examples of such a world in our own solar system, although the small gas giants Uranus and Neptune are similar in some respects.

Ammonia-based life? Yes, really.

GURPS Space, Ammonia Chemistry posted:

In that cold environment, it’s possible for something like Terrestrial nucleic-acid chains to function, or for complex chains of nitrogen or carbon and nitrogen to serve the same purpose. Since complex nitrogen molecules become highly unstable at liquid-water temperatures, ammonia-based organisms could be made of living high explosive! (This does not require the Explosive disadvantage, however, because the temperatures involved would kill the being long before its molecules became unstable.)

Ammonia-based life could conduct photosynthesis if it evolved on a cold Earth-type planet, or might tap the heat differential between layers of a gas giant world’s atmosphere. Such creatures probably would not be oxygen-breathers, since the chief source of oxygen molecules for Earth-type life (carbon dioxide) is a solid at ammonia-life temperatures. Instead, ammonia-based organisms might breathe free hydrogen, either in a gas giant atmosphere or liberated from methane molecules on a cold Terrestrial world.

So we already know something about our aliens, even though we haven't rolled anything past this: they live at extremely cold temperatures, are made of carbon and nitrogen, and probably breathe methane.

The next roll gives an atmospheric mass for the planet of 0.9 . (The 0.9 doesn't really represent anything on its own; it's just an arbitrary factor.) "The atmosphere of a Standard (Ammonia) world is composed of nitrogen, with large quantities of ammonia and methane. Such an atmosphere is always Suffocating, Lethally Toxic, and Corrosive." (These traits apply to the GURPS default - that is, humans - and our aliens will be automatically adapted to it.)

The planet's hydrographic coverage is (using 2d6 * 10%) 90%. This isn't liquid water, but instead "liquid ammonia mixed with water and other substances, mingled in a eutectic solution whose freezing point is much lower than that of pure ammonia or water." So, this is a pretty heavily ocean world, with some island chains or partial continents and such here and there.

As a Standard (Ammonia) world, the world's average surface temperature potentially ranges from 140 K to 215 K (or, -208° F to -73° F). Rolling for it gives an average surface temperature of 165 K (or -163° F). This leaves the world as a Frozen world by any normal standard.

The world's blackbody temperature (the average surface temperature the world would have if it were a perfect absorber and radiator of heat) is the average surface temperature, divided by the blackbody correction (the absorption factor for a Standard (Ammonia) world of 0.84 x [1 + (the atmospheric mass of 0.9 x a Standard (Ammonia) world's greenhouse factor of 0.20)]) of 0.9912. This results in a blackbody temperature of 166.46 K (not much different!).

For more context here, the blackbody temperature gets used in later calculations in place of the normal temperature, which can have quite a variance between them in the case of things like greenhouse or ice-covered worlds.

As a Standard (Ammonia) world, the planet's going to have any icy core . Rolling for it gives a world density of 0.5 Earth densities. Using the conversion factor given, this means the average density of the world is 2.76 grams per cubic centimeter.

The minimum diameter of the world is (the square root of [blackbody temperature / world density]) x 0.030 = 0.55 Earth diameters. Maximum is the same except with a maximum factor of 0.065, so 1.18 Earth diameters. Rolling for the difference in between gives a world diameter of 0.87 Earth diameters, or 6899 miles.

The world's surface gravity is (its density x world diameter), which gives 0.44 G.

The world's mass is (density x [diameter ^ 3]), which gives 0.33 Earth masses (or 1.97 x 10^24 kg).

Remember that atmospheric mass from before? Now we use it to calculate atmospheric pressure , which is (atmospheric mass x pressure factor of 1 x surface gravity), so 0.40 atm. This means the planet has a Very Thin atmosphere.

The planet's base resource value is rolled to be Abundant, which gives a +1 resource value modifier . Its habitability is a -1 in total (Suffocating, Lethally Toxic, and Corrosive atmosphere gives -2, and 90% hydrographic coverage means a +1). The planet's affinity score, which gives a general idea as to how much human-standard people might want to settle there, is just those other two scores added together, so it's a 0. (The best you can get is a terrestrial planet that's Rich, has a Standard atmosphere, 60% to 90% hydrographic coverage, and a climate between Chilly and Tropical, for a total +10 affinity score.)

As already decided, this is going to be a homeworld . (The section on settlement types notes that most worlds will automatically "be a colony if it is in a region of space claimed by some space-traveling civilization, it has an affinity score greater than 0, and it is not already defined as a homeworld.")

To make it easy, I've decided that this planet is isolated from any other theoretical star-spanning civilizations. Rolling randomly means that it is a Primitive world, and then rolling from there gives an average Tech Level for the planet of 4. TL 4 corresponds to the Age of Sail in humanity, from 1450 AD onwards. This means stuff like muskets, three-masted sailing ships, basic understanding of cellular biology, and so on. How does any of this stuff work on a planet that's constantly at -163° F? I have no idea!

The world's carrying capacity , based on its TL, affinity score, and world diameter, is 529,830.

GURPS Space, Determining Carrying Capacity posted:

This is the maximum population that the world can support in reasonable comfort for long periods of time. A world’s population can exceed its carrying capacity, but only at the cost of widespread poverty or the risk of a disastrous “die-back.”

This may get changed later, because certain species traits (carnivores, for example) modify the safe carrying capacity.

The world's population is based directly on its carrying capacity, since it's a homeworld. Rolling for it gives the oddly specific population of 476,847 individuals. This gives a population rating of 5.

Rolling for world unity and adding a bonus from the population rating gives a factionalized world.

GURPS Campaigns, The Big Picture posted:

Factionalized: A small number of rival “blocs” or superpowers dominate the world. Each bloc has enough economic and military might to rule the world, but the other blocs would sooner unite in opposition than let that happen. As a result, alliances shift regularly. Ties within blocs are more permanent.

And then rolling for dominant society type gets an anomalously high result, which gives... a Corporate State?

GURPS Campaigns, Society and Government Types posted:

Corporate officers rule the society. Most citizens are employees of the corporation. Society runs smoothly – it has to, or it can’t be profitable! CR4 to 6.

Welp. Methane-breathing icy Renaissance spacemen driven by the power of capitalism, I guess.

The world's Control Rating is from CR 4 to 6, based on its society type. At CR 4, this is one step more regulated than, say, modern America, requiring costly licenses for things like drugs, medical equipment, and hunting guns. At CR 6, the aforementioned are illegal for everyone except the military or secret police.

Welp. Methane-breathing icy Renaissance spacemen driven by the fear engendered by living in a locked-down police state, I guess.

Based on its tech level, affinity score, population, and carrying capacity, the world's per-capita income is $5,760 GURPSbucks. (This doesn't correspond to any real-world currency; the $ is just used as a symbol to denote cash amounts instead of game-points amounts.) Compared to "average TL4", this leaves most people on Planet Renaissance Capitalist Iceman at a Wealth level of Struggling. The planet's economic volume , based on per-capita income and population, is $2,746,638,720.

Next time: Crazily complicated star system stuff!

oh god, the physics

posted by anagramarye Original SA post

GURPS Space, Part 2—or—oh god, the physics

Remember when I said this book was thorough?

I'm just going to quote this entire section, because (a) this stuff is going to be important for later reference, and (b) so you'll understand how thorough I'm talking about.

GURPS Space, Stellar Classification posted:

Stars fall into a few very well defined groups according to their physical properties. Astronomers classify stars using their spectral class, essentially a way to sort stars by color and size.

The first component of the spectral class is the star’s spectral type or
“color,” denoted by a single letter. The most important spectral types are O, B, A, F, G, K, and M – remembered by astronomers using the jingle “Oh, Be A Fine Girl, Kiss Me!”

The sequence of spectral types also defines the relative surface temperature and luminosity of stars. O and B stars are hot and bright, while K and M stars are cool and dim. Spectral types are sometimes referred to as “early” (toward the bright, hot end of the range) or “late” (toward the dim, cool end). This nomenclature comes from the early days of stellar astronomy, when it was widely believed that all stars began their lives as O or B type and slowly moved down to K or M type before dying. This theory of stellar evolution has long since been discarded, but the “early-late” jargon persists.

The spectral type can be further specified by a decimal classification, using the digits 0 through 9. A subtype of 0 indicates a “standard” star of that spectral type, while subtypes 1 through 9 indicate progressively cooler, dimmer stars. Sol, for example, is of spectral type G2, and can be considered two-tenths of the way between a standard G-type and a standard K-type star.

The second component of a spectral class is the star’s luminosity class or “size,” which is denoted by a Roman numeral. Luminosity and size are related; two stars with the same spectral type (i.e. the same surface temperature) will be of different brightness if one is larger and has more surface area to radiate energy with. The luminosity classes are I (for “supergiant” stars), II and III (for giant stars), IV (for a class of “sub- giant” stars), V (for average-sized “main sequence” stars), and VI (for a rare class of “subdwarf” stars). Sol, for example, is a G2 V star.

One set of stars doesn’t fall into this classification scheme: the white dwarf stars. In a sense, these are not stars at all. A white dwarf is the remnant of a star that has finished its stable lifespan, has passed through a period as a giant star, and is now unable to continue fusion

burning. Stars that die in this fashion lose much of their mass, in processes that can be quite violent. The most common remnant of such a star-death is a white dwarf, a small but extremely dense body that shines dimly due to the retained heat of its final collapse. Astronomers use an elaborate classification scheme for white dwarf stars, but this book simplifies by assigning them all the luminosity class D without spectral type.

In the region of space around Sol, most stars are of luminosity class V. These are stars in the main part of their stable lifetime, burning hydrogen fuel and evolving very slowly, most of them across billions of years. About 90% of nearby stars are main-sequence stars (p. 104), and most of the rest are white dwarfs.

One very interesting thing about this random-roll system is that you can go either way—start with a planet and create a star system to put it in, or make a star system and randomly generate every planet.

The first roll in this section is for number of stars , which gives us 2 stars in the system—a binary system.

The primary star mass is another set of two rolls, and a crazy-low roll results in 1.70 solar masses (scaled off the Sun). The secondary star is based on the primary's mass, with some variation—getting a 1 means the roll gives the same as the primary, 1.70. If this was being generated for a Garden world (the "pretty and Earthlike" category), a special exception would have guaranteed that the primary had between 1.50 and 0.75 solar masses.

The system's stellar age is rolled to be a Young Population I system. Rolling for the actual age puts the system's age at 0.6 billion years (or 600 trillion years)... this is a young, young, young system (ours is 4.5 billion years old, for comparison). This is a good thing for the inhabitants, seeing as stars as big as these two tend to burn out pretty quick, turning into giant stars on the order of 2 billion years old.

As both stars are firmly in the main sequence, their spectral type (by mass) is A9, with an effective temperature of 7,500 K. Calculating their luminosity results in 9.0 for each—that is, 9 times brighter than our Sun. Given the temperature of the planet we've already calculated, this is going to put it in a pretty far-out orbit, with a crapload of further-in planets in-between. They both have an identical star radius of .0083 AUs.

Another roll puts the secondary star's orbital separation at Distant. Rolling for the actual distance means that it's 250 AUs from the primary—for an example, about eight times farther from its primary than Pluto is from our Sun. Rolling for its stellar orbital eccentricity gives the actual minimum/maximum distances between them as 125 AU and 375 AU respectively.

This gives an interesting situation; another random roll shows that the secondary star has its own companion orbiting it. Going back a couple of steps and then running through some of the star generation stuff again (using the same age for the star system) results in that sub-companion having a solar mass of 1.15, a spectral type of F9, an effective temperature of 6,100 K, and a luminosity of 1.51. It has a star radius of .0051 AUs, and, rolling again, the sub-companion is Close to the system's companion star, turning out to be 2.5 AUs from it. The orbital eccentricity roll and calculation again shows its actual min/max distance to be 1.75 AUs and 3.25 AUs respectively.

The primary's inner limit radius , the distance at which it's too close for any planets to form or stably orbit long-term, based on its mass, is 1.7 AUs. The primary's outer limit radius , beyond which planets are unlikely to form, is 68 AUs. For the companion star, these figures are also 1.7 AUs and 68 AUs; for the sub-companion, they're 0.12 AUs and 46 AUs respectively.

The primary's snow line (more math, using the star's initial rather than current luminosity) is at 14.22 AUs—this is where ice is present during planet creation, and gas giants and other similar planets will start to form. For the companion star, this is also 14.22 AUs; for the sub-companion, it's 5.96 AUs.

Based on the orbit of the secondary star, the primary's forbidden zone ranges from 41.67 AUs away from the primary to 1125 AUs away. Because this overlaps the primary's outer limit, this will empty out some potential outer orbit space. The companion and sub-companion stars' forbidden zones are from 0.58 AUs to 9.75 AUs because of each other, and then from 41.67 AUs to 1125 AUs again, based on the primary.

Now, finally, it's time to start adding planets in—planets for both primary and companion stars. But before I do that, I'm going to give you a chart of what this system is like so far, just to make sense of it.

pre: 
primary star (0 AUs)
mass 1.70, luminosity 9.0, radius 0.0083 AUs

-- inner limit (1.7 AUs) --

potential orbits (1.7 AUs to 14.22 AUs)
orbiting primary

-- snow line (14.22 AUs) --

potential orbits (14.22 AUs to 41.67 AUs)
orbiting primary

-- forbidden zone starts (41.67 AUs) --

-- outer limit (68 AUs) --

companion star (125 AUs to 375 AUs)
mass 1.70, luminosity 9.0, radius 0.0083 AUs

    -- forbidden zone starts (0.58 AUs) --
    
    -- inner limit (1.7 AUs) --
    
    companion star (1.75 AUs to 3.25 AUs)
    mass 1.15, luminosity 1.51, radius 0.0051 AUs
    
        -- forbidden zone (0.58 AUs+) --
        
        -- inner limit (1.7 AUs) --
        
    -- forbidden zone ends (9.75 AUs) --
    
    potential orbits (9.75 to 14.22 AUs)
    orbiting companion and sub-companion simultaneously
    
    -- snow line (14.22 AUs) --
    
    potential orbits (14.22 to 41.67 AUs)
    orbiting companion and sub-companion simultaneously
    
    -- forbidden zone starts (41.67 AUs) --
    
    -- outer limit (68 AUs) --
    
    -- forbidden zone ends (1125 AUs) --

    no orbits here (too far)

-- forbidden zone ends (1125 AUs) --

no orbits here (too far)
Holy crap.

Ahem.

Gas giants come first—the book is written to use the "best guess" of modern astronomy, which include gas giants potentially existing very close to a star, in clear contradiction of the classic cosmological models most people are used to.

A random roll puts the gas giant arrangement for the primary as including an epistellar gas giant—one of those ones I just mentioned that's crazy-close to a star. The companion has No Gas Giant (it might get them later, but there's no special arrangements for it).

GURPS Space, Epistellar Gas Giant posted:

At least one gas giant planet has migrated down to a very tight circular orbit around the primary star. This gas giant may have absorbed some of the material available for building rocky planets, but such planets may have been able to form anyway after the gas giant finished its migration. Other gas giants may exist in the outer star system, as in the conventional arrangement.

Rolling for its distance from the primary gives it at 11.9 AUs. This is inside the snow line, making it a "hot giant".

Now it gets to the step where I plug in that world I already have. Some math (again)—(77,300 / blackbody temperature squared) × square root of solar luminosity—gives its orbital radius, based on blackbody temperature and the star's luminosity, as 8.42 AUs.

A side note: Yes, it's entirely possible to get to this step and then have a world that won't fit because there's already a gas giant in the way/the star is too dim to allow it/whatever. It already happened to me earlier (thus my note in the thread).

Now that the first gas giants and the predesigned world are placed, it's time to figure out the orbital radii for all the system's other planets/planetoids. This involves multiplying or dividing each orbit by a slightly randomized ratio to get each outward or inward orbit in sequence, out to the outward limit and to the inward limit, going from the gas giant. This also takes a little bit of tweaking to make sure that orbits for the gas giant and for the predesigned world fit nicely into the orbital ratios.

Then it's time to fill in each of the orbits—again, rolling randomly, with some modifiers based on what the orbit is adjacent to. Gas giants get first pick (except for the companion sub-system, since it had a No Gas Giant result), and then other possible things (asteroid belts, planets, etc).

Going through all of this results in:


It's time to generate moons now! More random rolls (lots and lots and lots and lots and lots and lots), for each gas giant and then for the rest of the planets, results in...


GURPS Space, Gas Giant Moons posted:

The first family is a cluster of moonlets orbiting close to the planet. These moons orbit very close together, sometimes even sharing orbits in a “resonant” pattern that prevents their collision.

...

The size of this first family of satellites will determine the level of ring system the planet has. If a gas giant planet has at least 6 satellites in this family, its ring system will be visible from anywhere in the star system, at least in moderately powerful telescopes. If there are 10 or more satellites in this family, the ring system will be comparable to Saturn’s, easily visible even in small telescopes from a distance and spectacular from close up.

...

The last family is another group of moonlets, captured asteroids that are often in eccentric, highly inclined, or even retrograde orbits.

Now, guess what?

That's right, more math ! This is the step where you determine the details of each world that's not already predetermined. The system does it rather cleverly, at least—you use the star luminosity and orbital radii to determine the full world type of every moon and terrestrial planet in the system, without needing (many) more random rolls (the ones there are are basically just coin flips between two equally likely world types). Once the world types are determined, one can go back and figure out atmosphere, hydrographics, temperature, size, etc etc as it was done for the pregenerated world, except slightly in reverse (working from the blackbody temperature backwards).

This is also where it finally gives the way to calculate mass, density, diameter, and cloudtop (instead of surface) gravity for gas giants. They use their own special random roll chart for mass and density.

This step is also where planetary and stellar orbital periods, planetary orbital eccentricity, satellite orbital radii, etc etc etc, are generated. This is a shitload of math and rolling and cross-checking modifiers and crap, so I'm skipping showing all these steps in-between because it would just be an exercise in pure, distilled tedium.

Going through the whole process yields a completed result:

look at all those details

posted by anagramarye Original SA post

GURPS Space, Part 3—or—look at all those details


Something complete ridiculous has happened here, as you might have noticed: somehow I got a natural 17 (on 3d6) while rolling for that other Standard world, making it a Garden world instead of just a lifeless and oxygen-less Ocean world. This is extremely unusual for a star system so young. So, yes, that means there's potentially two separate and unrelated kinds of life in this one star system, neither of which can even survive on the others' world. Not only that, but it would potentially be extremely attractive for human habitation... if you don't mind it being tide-locked to its moon. If it hadn't had a moon generated, it would have ended up tide-locked to the star, making the day side noticeably hotter and the night side noticeably colder all the time.

You can also see that both potentially inhabited worlds have both volcanic and tectonic activity on the heavier end of things.

GURPS Space, Volcanism posted:

Heavy: Volcanism is very common across the world’s surface. There may be regions where individual volcanoes cluster and merge, permitting magma to well up through great wounds in the crust. New volcanoes appear every few years. There is plenty of volcanic “recycling” of trace elements in the environment.

Extreme: The world’s surface is dominated by volcanism. The planet’s surface is generally unstable, and new volcanic eruptions can take place almost anywhere and at any time. The atmosphere is very unlikely to be breathable, even if it would otherwise have the proper composition. There is plenty of volcanic “recycling” of trace elements in the environment. Examples in our own solar system include Jupiter’s moon Io.

If a Standard (Garden) or Large (Garden) world has Heavy or Extreme volcanism, this may render its atmosphere Marginal. In this case, the most likely contaminants for the atmosphere are sulfur compounds or pollutants. Set the atmosphere to Marginal as needed. To test this possibility at random, roll 3d; if the roll is an 8 or less (for Heavy volcanism) or a 14 or less (for Extreme volcanism), the atmosphere is Marginal regardless of any results obtained earlier.

GURPS Space, Tectonics posted:

Heavy: The world’s crust is divided into many plates. Crustal quakes can be very powerful and can be experienced almost anywhere on the world. Almost all volcanoes are small ones of the “chain” or “arc” type. Mountain- building is almost constant, and most of the world’s mountain ranges are likely to be young and high.

Extreme: The world’s crust is fragmented and unstable. Crustal quakes are powerful, and can be experienced anywhere on the world at any time. Landforms are likely to be highly chaotic, including a large number of very young, high mountains.

Actually, the worlds' young ages made heavier-than-Earth volcanism pretty much inevitable (the volcanism roll has a hefty modifier based on surface gravity divided by system age in billion of years); it was the Garden world's Earthlike gravity that shot it off the bottom of the chart into the Extreme category. Then the volcanism modifier and the presence of moons boosted up tectonics enough to inevitably be higher than Earth's.

The upside of all this vulcanism is that it's bumped both of these planets' resource value modifiers up (requiring a reroll for Planet Ice People - a 16 on 3d6, +1 from the volcanism, puts them into Very Abundant), though the high-end volcanism and tectonics also puts a penalty on the habitability scores. (Small and Tiny planets never have any tectonics, so their habitability is unaffectedby that, though volcanism still gives a penalty.)

This change in Planet Iceman's affinity score also means a change in the carrying capacity and (since it's based on that) the total population, the changes of which I've included above. I also realized I was dumb and only using the normal-human modifiers, so I added a special "for nitrogenpeople" rating, giving them atmosphere/"water" modifiers based on their biology. This bumps their effective affinity score waaay up, increasing the population quite a bit.

And the increased population prompts a reroll for world unity , turning it into Diffuse instead of Factionalized. The world's dominant Society Type stays the same, though, at it's not affected by population.

GURPS Campaigns, The Big Picture posted:

Diffuse: There are dozens, if not hundreds, of clans, nations, and groups. No one can make any claim to world domination.

This does bump up the per capita wealth though, all the way to... $6,900 GURPSbucks a head, because the population is now well over the carrying capacity.

Next time - actually rolling up some aliens!

Edit: Fixed some placeholders I left in.

finally, some Goddamned aliens up in here

posted by anagramarye Original SA post

GURPS Space, Part 4—or—finally, some Goddamned aliens up in here

After that whole process of putting together a system, rolling up some aliens is actually... really easy, by comparison. It's mostly just some straight-up 3d6 rolls here and there with modifiers from previous results.

As it's an ammonia world, the chemical basis is already selected for us. There's a 3d6 roll here that could be otherwise used (and you could use that to roll up an alien species, then go backwards and pick a suitable world type to generate for it).

GURPS Space, Ammonia Life Mechanical Traits posted:

Living creatures based on ammonia should define their Temperature Tolerance range as centered some- where between -100° F and -25° F; they are not automatically Cold- Blooded in the sense defined by the disadvantage of that name, however. Hydrogen-breathers may take the disadvantage Fragile (Combustible) if they spend lots of time in oxygen environments, as their “air” can catch fire. Since chemical reactions are slower at ammonia temperatures, either a low Basic Speed or Decreased Time Rate might be appropriate.

The next roll (1d6, +2 for 90% hydro coverage; a 4+ is water-dwelling) tells us that these aliens have a habitat that's... water-based. Okay, uh, I have no idea how a water-dwelling TL4 civilization works, but whatever. Rolling for specific type (3d6) gives a result of Banks.

GURPS Space posted:

In the ocean, Banks are coastal waters where nutrients are abundant. They can support a great deal of life; on Earth they are the great fisheries. One can call banks the marine equivalent of plains, since they have lots of food but most of the animal life is quite mobile.

Underwater farmers, maybe?

This section is also used for life in gas giants, always using the "water" result—the intent being that you use the same mechanical modifiers, then figure an analogy for it. The exotic life result also gives the option to use the "water" table to roll for plasma-dwelling life in the surface of a star.

Next, a 3d6 roll for trophic level —using a secondary table specifically set up for intelligent life—gives Omnivore. No special explanation needed for that, I think. At the extremes of the table are weird options like Parasite/Symbiont (also self-evident) or Decomposer (like mobile predatory plants or shoggoth-esque super-slime molds).

A roll for primary locomotion (with a bonus from being omnivores) has our underwater nitrogen-people having winged flight. This also gets them a roll for secondary locomotion , which turns out to be swimming... which gets them a roll for tertiary locomotion , which is walking. They're like those cool Transformers toys with three modes, I guess.

GURPS Space, Walking posted:

A creature’s walking speed depends on the length of its legs and the local gravity. Specifically, speed is proportional to the square root of leg length times gravity. This means that one can generally run faster in high gravity, because the higher gravity makes you take faster steps. To convert this to GURPS terms, Move for aliens equals 5 times the square root of (L x G), where L is the aliens’ height or length divided by human height of 6 feet, and G is the local gravity in gees.

...

Note that really big animals like elephants or the larger dinosaurs never move faster than a walk or a trot, because would put too much stress on their bones. That doesn’t matter because they can walk pretty fast anyway because of their long legs.

GURPS Space, Winged Flight posted:

Wingspan for flying creatures depends on their weight and the atmospheric density. For a rough rule of thumb, divide weight (in local gravity) by 30 lbs. and take the square root, then multiply by 10 feet. This can vary by as much as 25% depending on what kind of flyer the creature is – long-range ocean flyers have long, narrow wings, while fast and maneuverable flyers have shorter ones. Wingspan goes down in denser air and up in thinner. Very long wingspans are difficult to make with biological materials; among birds the record is 17 feet for the Pacific albatross, and for fossil pterosaurs the widest known span is 35 feet for Quetzalcoatlus. That’s probably about the maximum possible for Earthly bone and flesh. Note that flyers that never land could have better-designed wings and a span of perhaps 50 feet.

Time to roll for size category . That's a straight 1d6, with a -3 for winged flight, but a +2 for the planet's low gravity, and another +2 for living in/on ocean banks. It comes up as a 5, Large. A 3 on the 1d6-roll subtable gives the size as 10 yards, with a Size Modifier of +4 and an average weight of 12 tons (on Earth; 5.3 tons on this planet). An extra size modifier based on the local gravity increases that to 18 yards, bumping up their size modifier to +5, and giving an average weight of 72.9 Earth tons (or 145,800 Earth pounds, or 64,152 local pounds)

So, uh, this means that they have a wingspan of (sqrt(64152/30)*10=) 462 feet, or thereabouts. Also, average Strength scores of 80. (A human has ST 10, for comparison... and it's an exponential progression.)

The next roll for body symmetry makes them bilateral (the table also includes such options as Spherical or Radial). Rolling for number of limbs gives them 2d6 "segments", with one limb per side per segment; rolling for that means 6 segments, so 12 limbs total. A roll for a tail (with a bonus from being a swimmer) gives them one, and it turns out to be a constricting tail (giving a mechanical Constriction Attack trait).

The roll for manipulators (using 1d6+6 instead of 2d6, adding +2 because of all those limbs, and -1 because of being winged) results in "1d sets of manipulators"; rolling for the details on those gives 5 sets of manipulators, 2 of which have High Manual Dexterity.

The next roll, for skeleton type (with a bonus from Large size, and a penalty from low gravity) results in an external skeleton.

GURPS Space posted:

An External Skeleton uses a shell made of some rigid material that can be jointed to allow movement. This is a very successful design, as the hard shell protects the soft interior of the organism. However, growth is difficult because the organism must shed its old skeleton to grow a bigger one, leaving it vulnerable during the change. Aliens with exoskeletons may have evolved a way to grow without molting. Without a buoyant medium for support, large external skeletons can become very heavy and cumbersome.

...flying crabwhales?

Since there's an exoskeleton, the species' outer covering is automatically, well, an exosekeleton. The next roll shows that it's a tough exoskeleton (mechanically, Damage Resistance 1).

The roll for breathing , with a bonus because of walking as a secondary locomotion type, has these flying crabwhales as having both gills and lungs, so I guess they're equally at home in the water and the air.

Rolling for temperature has them as "warm-blooded" (or the equivalent in the planet's chilly climate; some kind of active metabolic regulation, rather than depending on surroundings).

Their growth pattern (the roll has a penalty from the exoskeleton, but a bonus from Large) has Continuous Growth.

Rolling 2d6 on a table for the number of sexes has a "roll twice" result ("types either alternate or are triggered by conditions"), so doing that gives Two Sexes and Hermaphrodite results. Er, okay...

The gestation method , as adjusted for being amphibious, is that they're Egg-Laying. A secondary roll to see if there's a special gestation method falls short, so that's it.

The reproductive strategy roll, penalized by being Large, results in a Strong K-Strategy ("one offspring, extensive care after birth").

GURPS Space posted:

K-strategist organisms have few offspring, but invest a great deal of resources and energy in rearing them and making sure they survive to adulthood. K- strategists also tend to live a long time, so that they have the chance to have more than one offspring.

Rolling for the primary sense gives Hearing. This doesn't automatically affect other sense types; rather, the primary sense gets a big positive modifier on rolls for the sense tables.

Vision gets a modifier anyway because of flying, and a 17 results means that their sight is so good they all have 4 points in Telescopic Vision.

Rolling for hearing (with that primary modifier) gets... another 17, which means 4 points in Acute Hearing, plus Ultrasonic Hearing and Sonar.

Touch gets a penalty because of the exoskeleton, and another penalty from flying; that they get a -2 to Dexterity across the board because of their bad sense of touch is practically inevitable (and the result's only one point away from the entire race being Numb).

Rolling for taste/smell (with a small bonus because they sexually reproduce) has them as having 4 points in Acute Taste/Smell and the Discriminatory Taste/Smell trait (which is the trait that lets, say, animals track by scent).

Now it's time to roll for special senses ; each just gets a 2d6 roll, with an 11+ indicating the species has it. There's also some small modifiers from habitat type and such. As it turns out, our nitrogencrabwhales have 6 points in Night Vision.

This smorgasbord of highly-tuned senses means I have to roll for each one to see which is the dominant communication channel . This is, as it turns out, their hearing, with taste/smell being the secondary communication channel.

Next comes rolling for intelligence . This uses a special roll for sapient beings, which is just 1d6+5, +1 for strong K-strategy. This comes up as 12, which will be the average racial Intelligence score (for comparison, humans have a 10).

Mating behavior , which gets a small bonus from K-strategy, gets a 9 - harem behavior.

GURPS Space posted:

Males sometimes try to monopolize all the available females by driving away or killing any rival males. This “harem” system is particularly common in species that gather in groups anyway, like plains grazers. The advantage is that the strongest male fathers many children, and the females often cooperate in caring for the offspring. Harem species often have a noticeable difference between the sexes, with males typically large and bristling with weaponry to fight off challengers. In some harem species the males and females live apart except during mating season.

Social organization , which gets a penalty from size and a bonus for harem mating, comes up as a "small herd". (Note that this is only the "wild" instinctual behavior; the actual society is likely to be as unnatural, compared to non-intelligent animals, as ours is.)

GURPS Space posted:

Huge groups of animals (10-100 or more) are known as herds, schools, or flocks. On Earth they are typically found among grazers, since a huge group requires a huge food supply. Small herds may be a harem, but really big herds are simply too much for even the most ambitious male to monopolize. Herds don’t seem to have as much of the hierarchy found in packs; the biggest or oldest members may be the herd leader, but that seems to be “merit-based” rather than “political.”

The next set of tables don't actually have any rolls—they're just totaling up modifiers and comparing them. These determine the species' collective "personality" as compared to humans; this doesn't necessarily impact any particular member of the species, but it gives an idea of what the usual tendencies are.

Their chauvinism (as a racial group, that is, comparing themselves to other species), because of naturally organizing into small groups, is Chauvinistic at the quirk level (eg. a single-point disadvantage).

Their concentration , because of that K-strategy, is Attentive at the quirk level.

Their curiosity , because of being omnivores and having a strong K-strategy, is Curious (12) - that is, the Curious disadvantage at a control number of 12.

GURPS Characters, Curious posted:

Make a self-control roll when presented with an interesting item or situation. If you fail, you examine it - push buttons, pull levers, open doors, unwrap presents, etc. – even if you know it could be dangerous. Good roleplayers won’t try to make this roll very often...

Their egoism is Proud at a quirk level... or the Selfish (12) disadvantage for males, because of harem-strategy reproduction.

GURPS Characters, Selfish posted:

You are self-important and status- conscious, and spend much of your time striving for social dominance. Make a self-control roll whenever you experience a clear social slight or “snub.” On a failure, you lash out at the offending party just as if you had Bad Temper (p. 124) – likely resulting in a bad reaction (-3 to the target’s reactions toward you) and putting you in an awkward social situation.

The empathy level is (from small-group organization and K-strategy) the Empathy (Sensitive) advantage.

GURPS Characters, Empathy posted:

You have a “feeling” for people. When you first meet someone – or are reunited after an absence – you may ask the GM to roll against your IQ. He will tell you what you “feel” about that person. On a failed IQ roll, he will lie!

...

Sensitive: Your ability is not entirely reliable; the IQ roll is at -3. You get +1 to your Detect Lies and Fortune-Telling skills, and to Psychology rolls to analyze a subject you can converse with.

Their gregariousness is just Normal.

Their imagination , from K-strategy and being omnivores, is Imaginative at the quirk level, plus the Dreamer quirk because of their egoism.

Their suspicion , because of being Large, is in the negatives; they have 1 point in Fearlessness.

Their playfulness rating, from strong K-strategy and high IQ, has them at Compulsive Playfulness (9).

GURPS Characters, Compulsive Behavior posted:

You have a habit – often a vice – that wastes a good deal of your time or money. You must indulge at least once per day, if at all possible, and do so any time you have the opportunity unless you can make a self-control roll. You seek to avoid any situation where you know you will be unable to indulge for more than a day. You must make a self-control roll to enter into such a situation; if you succeed (or are forced into the situation), you suffer from Bad Temper (p. 124) the whole time, with the same self-control roll as your Compulsive Behavior. It’s bad roleplaying to try to avoid your compulsion regularly!

Nitrogencrabwhalebird

posted by anagramarye Original SA post

Nitrogencrabwhalebird (180 points)


I think I got everything. Did I get everything?

Edit: No I didn't. Will update in a minute.

Edit edit: Okay, now I think I got everything.

An example alien (Garden-type planet)

posted by Piell Original SA post

Planet info posted:

orbit 2 (2.93 AUs): Terrestrial Planet (Standard [Garden]). Atmos mass 1.1 (Marginal/nitrogen with oxygen and sulfur compounds/Mildly Toxic), atmos pressure 1.056 atm (Standard), temp 291 K (Normal), BB temp 281 K; hydro coverage 70% (liquid water); density 1.1, diameter 0.87, mass 0.73, surface gravity 0.96 G; RVM +0 (Average), habitability +3, affinity +3. Orbital period 3.85 years; orbital eccentricity +/- 0.29 AUs. Star tidal force 0.027; moon tidal force 1,780; total tidal effect 1,463.04. Rotation period 2.43 days (tide-locked to moon). Axial tilt 35°. Volcanic activity Extreme; tectonic activity Extreme.

* orbit 2.1 (12.5 × planet's diameter): Moon (Tiny [Rock]). Atmos mass 0 (vacuum), atmos pressure 0 atm, temp 273 K (Chilly), BB temp 281 K; hydro coverage 0%; density 0.7, diameter 0.32, mass 0.023, surface gravity 0.22 G; RVM +1 (Abundant), habitability -1, affinity +0. Orbital period 2.43 days. Planet tidal force 3,233.00; total tidal effect 84,339.13. Rotation period 2.43 days (tide-locked to planet). Axial tilt 13°. Volcanic activity Heavy; tectonic activity None.

Alright, let's start by generating the Social Parameters. I'm going to choose the settlement type as Homeworld. Like the other planet in the system, it's isolated from any star-faring civilizations. Rolling gives me a result of 5, meaning Standard-2, or and with a standard TL of 11 that gives us a Tech Level of 9, or near-future tech. Based on their TL, Affinity, and world size, the carrying capacity is 90,828,000. The actual population is 151,380,000, giving us a population rating (PR) of 8.

Now we move on to Society Type . Their world unity ends up as Factionalized, and rolling for dominant society type gives us Dictator. Might makes right, apparently. The world's control rating ranges from 3 (moderate restrictions), which would be similar to modern America, all the way to CR 6 and total control. The per-capita income is $34,400 GURPbucks, which is average for a TL9 society.

Now that that's settled, let's see what these advanced technology dictators actually look like. The chemical basis is water-based life, just like that on Earth. The overall habitat is land-dwelling despite the high amount of water, and the specific land habitat is Island/beach. their trophic level gives us Gathering Herbivore. Looks like we may have some picky eaters!

GURPS Space posted:

Gatherers consume high-energy food. Often this means they must go to a lot of trouble to find it. Some gatherers specialize in a single food, and develop highly specialized organs to locate and harvest it. Others prefer to generalize.

Their Primary Locomotion turns out to be Climbing, which leads us to a Secondary Locomotion of Walking. When I see Island/Beach and climbing combined with the amount of water and the level of volanic activity, I'm thinking cliff dwellers of some kind, possibly. Their Size Category is a 1d6, minus 1 for being island/beach creatures, which gives us human-scale, 18" to 3 yards, and their Size Turns out to be 1.5 yards and 80 pounds, or -1 Size Modifier, so slightly smaller than humans. Their gravity is 0.96, so no modifier to that.Their Strength is 9 (10 is human average).

Rolling 2d6 for symmetry gives us a 7, just on the edge of bilateral. Number of limbs is a 1d6, coming up 4 gives us 1d (which turns out to be 3) segments with one limb on each side per segment. The tails roll is a 3, so they do not have a tail. Now we move on to the number of manipulators . The roll is 1d6+6, +1 for more than 4 limbs, and +1 for a gathering herbivore gives us the minimum roll of 9, which is 1 set of manipulators with normal dex. their skeleton is a 2d6 roll, with a +1 for human scale and +1 for land-based. The roll is 8, giving them an internal skeleton (i.e. bones).

Skin starts with a d6 rolling, ending up with actual skin. We then move onto the subtable for Skin Type , and end up with Blubber, giving us DR 4 and 1 level of temperature tolerance. They're land dwellers, so they automatically breath air. The Temperature roll is 2d6, plus 1 for being air-breathers, +1 for being human-scale or larger, and +1 for land-dwelling. A roll of 10 means they are warm-blooded with Metabolism Control 2, meaning they can control normally involuntary biological functions such as pulse, blood flow, digestion, and respiration, and allows them to go into a deathlike trance to reduce their oxygen/food/water requirements. They have a continuous growth pattern

Rolling for number of sexes gives us two sexes. their gestation method (2d6, +1 for warm-blooded) gives us spawning/pollinating. The secondary roll for special gestation fails, so spawning it is.

GURPS Space posted:

Spawning is the method used by fish, amphibians, and many invertebrates; and it is analogous to the way plants reproduce. Organisms that spawn release their gametes (eggs or sperm) into the environment, and fertilization and development take place outside the body. Often females can lay thousands of eggs, in the hope that some will reach maturity. Obviously, spawning lends itself to r-strategy reproduction, although there are species in which one or both parents remain near the egg mass and do their best to protect and feed the young once they hatch.

The reproductive strategy roll gets a +2 for spawning, and their end result is an 8, meaning a moderate r-Strategy, meaning one or more of the parents gives some care after birth. The base number of young per litter gives us a 7, which is multipled by 2d6*10 for spawning, for a total result of 280.

Their primary sense is vision.

Vision gets a +4 bonus for being the primary sense, +2 for being climbing creatures, and +2 for being gathering herbivores. The total result is 15, giving them Telescopic Vision 4.

Hearing is a straight 3d6 roll, giving us Normal Hearing with extended range (Ultrahearing, since we aren't large). They can hear sounds in the frequencies above the normal human range, like dogs whistles.

Touch is another roll for no bonuses, but I roll high and end up with Acute Touch 4. They are very good at distinguishing things by touch, which probably comes in handy for a climbing species.

Taste/Smell gets +2 for being gathering herbivores, and another +2 for sexual reproduction. A result of 10 gives us Acute Taste/Smell 4. Overall, they seem to have excellent senses.

Special senses is a series of rolls. They end up with Absolute Direction (possibly a magnetic sensing system, like some birds seem to have).

They have all sorts of good senses, so they have lots of options for their dominant communications channel . They end up with Sight as their dominant communications ability, with Touch as their secondary communication. They talk primary through gestures and body language, and touch each other for emphasis.

Now time to determine their intelligence . We have 1d6+5, +1 for gathering herbivore, giving them a result of 9 (again, 10 is human average).

Their mating behavior recieves a -1 for spawning and comes out 6. This is a temporary pair bond.

GURPS Space posted:

Other species have a temporary pair-bond, in which the parents remain together until the offspring hatch or are capable of fending for themselves. (On Earth this usually means one year.) Since these creatures have to attract a new partner each
year, they often go in for elaborate mating displays, especially the males. Males may also stake out prime territory or good nesting sites.

Social organization is a straight roll for them, and a result of 6 gives them a result of solitary. This is for the "wild" instinctual behavior, but they probably have a loner tendancy even now.

Now, we determine the group of mental qualities that determinds their collective species personality.

Chauvinism (as a racial group, that is, comparing themselves to other species) is a -2 because of spawning and solitary. They have quirk-level Broad-Mindedness.

Concentration is quirk-level distractedness because they are herbivores.

Their curiosity is normal.

Their egoism has a +1 for solitary, so they are Proud at a quirk-level.

Empathy comes out at Oblivious, because of their solitary nature.

GURPS Characters posted:

You understand other's emotions but not their motivations . This makes you awkward in situations involving social manipulation. You are the classic "nerd"!

Their Gregariousness gets -1 for herbivore, -1 for solitary, and -1 for spawning, giving us the lowest possible resulton the table. They are Loner, with a control number of 9.

GURPS Characters posted:

You require a great deal of "personal space." Make a self-control roll whenever anyone lingers nearby, watches over your shoulder, etc. If you fail, you last out at that person just as if you had Bad Temper.

Their imagination gets +1 for gathering herbivores, giving them Imaginative at the quirk level as well as Dreamer quirk because of their egoism.

Suspicion is +1 for solitary, meaning they have Careful as a quirk.

Playfulness is +1 for high IQ and -1 for solitary, leaving them normal.

pre: 
Attributes [-35]
ST 9 [-10]
DX 10
IQ 9 [-20]
HT 10

Basic Move 4 [-5]

Ground Move 4

Social Background
TL: 9 [-10]

Advantages [72]
Absolute Direction [5]
Acute Taste and Smell (4) [8]
Acute Touch (4) [8]
Damage Resistance (4) [20]
Extra Legs (4 Legs) [5]
Metabolism Control (2) [10]
Telescopic Vision (4) [20]
Temperature Tolerance (1) [1]
Ultrahearing [5]

Disadvantages [-7]
Loner (9 or less) [-7]

Quirks [-6]
Broad-Minded [-1]
Careful [-1]
Distractible [-1]
Dreamer [-1]
Imaginative [-1]
Proud [-1]

Stats [-35] Ads [72] Disads [-7] Quirks [-6] Skills [0] = Total [24]
So, overall, some sort of centaur-monkey-seal combo with great senses that likes to be alone.

An example alien (Silicon-type planet)

posted by Piell Original SA post

quote:

# orbit 1 (1.83 AUs): Terrestrial Planet (Tiny [Rock]). Atmos mass 0, atmos pressure 0 atm, temp 345 K (Infernal), BB temp 356 K; hydro coverage 0%; density 0.9, diameter 0.28, mass 0.02, surface gravity 0.25 G; RVM +0 (Average), habitability +0, affinity +0. Orbital period 1.90 years; orbital eccentricity +/- 0.18 AUs. Star tidal force 0.036; total tidal effect 1.08. Axial tilt 73°. Volcanic activity Moderate; tectonic activity None.

Ok, doing this planet. The settlement type is homeworld, as always. The modified hability score for the aliens is +7, as is the affinity . The technology level roll is 3d6-10, and ends up Primitive. This has me roll again, using 3d6-12, and so these aliens are TL 0, so they are a Stone Age civilization. The world's carrying capacity is 101,920 individuals. The actual population turns out to be exactly at carrying capacity, giving us a population rating of 5.

Now we move on to Society Type. Their world unity ends up as Diffuse, which isn't really unexpected. Rolling for dominant society type gives us Dictator once again. The world's control rating ranges from 3 (moderate restrictions), which would be similar to modern America, all the way to CR 6 and total control. The per-capita income is $6,750 GURPbucks, which is just below average for a TL0 society. Not sure what they are going to buy with it, maybe better rocks?

Now that that's worked out, let's start on the fun parts! Due to the planet's type, there are only two options, both silicon-based. We could have either sulfuric acid/silicon creatures, or liquid sulfur/silicon based life forms (these are opposed to Earth's typical water/carbon based life).

GURPS Space posted:

Sulfur-based life could use liquid sulfur as a solvent much as we use water. On Jupiter’s moon Io, vol canos pour out large amounts of sulfur, indicating the possibility of an underground “ocean” of liquid sulfur. In the absence of free oxygen, sulfur-based life could use carbon-sulfur compounds, fluorocarbons, or silicates as the basis of life. They could breathe hydrogen sulfide (the gas that makes the “rotten egg” smell) or free hydrogen.
Another possible solvent for sulfur-based life is sulfuric acid. On Venus, the clouds contain fairly large amounts of sulfuric acid, and it’s not
impossible to imagine a slightly cooler Venusian world with lakes or small seas of acid on the surface. Since a strong acid like sulfuric acid can dis-
solve rocks, sulfuric acid would also be a good medium for silicon-based life using sulfur chemistry for metabolism. Civilization on such a world might never develop metal-based technology, as only “noble metals” like gold would be able to resist the fantastic corrosion of an acid-laced atmosphere for very long. Instead one can imagine silicon-based organisms developing a combination of “biological” ceramics and silicones as their primary materials for tools and machinery.

A coin flip gives us sulfuric acid/silicon creatures. Now we need to roll a d6 to determine our habitat , with a -2 penalty for 0% ocean coverage. A result of 2 gives us land-dwelling creatures. We now roll for land habitat and a 15 means that they are jungle dwellers, living amongst the silicon-based trees. A roll of 11 on the trophic level gives us chasing carnivores. This cuts our carrying capacity (and also population) down to 10%, so 10,192 individuals.

GURPS Space posted:

Chasing hunters go after larger prey and invest a lot of energy in makng sure they get a successful kill. Often they work in groups and coordinate the hunt by well-developed communication methods. Chasers must have good stamina and senses, to keep up with a big prey animal until it falls from exhaustion. Solitary chasers are especially impressive in this regard: a Komodo dragon can hunt a deer for days.

The primary locomotion is a 3d6 roll, +1 for being chasing carnivores. They end up with walking, and no secondary form of locomotion. Our size class roll gets a +2 for the low gravity, and a result of 7 is Large. Our size is a base 15 yards and 40 tons. Silicon-based life has doubled weight, so our base weight is 80 tons. (in earth gravity), for a size modifier of +4. The low gravity acts as a multiplier, giving us 33 yards and 176 tons, or 44 tons in local gravity. Their strength is 44 (for comparison, an elephant has strength 45).

The symmetry is an 8 - giving us trilateral based life! The roll for number of limbs gets a -1, because of trilateral symmetry, and gives us 1 limb per side, so they are tripods. They have a tail , which is purely cosmetic (a 0 point advantage). The roll for manipulators is 1d6+6, since they are intelligent life, giving a result of 10. They have 2 manipulators on each limb - one with Bad Grip, and one normal. I expect the Bad Grip manipulator is the one typically walked upon, or it could be a talon or have large claws used for striking. The roll for skeleton gets +2 for being large, +1 for being land-dwelling, and -1 for low gravity, and we roll a 9, giving use a combination skeleton!

GURPS space posted:

Combinations of skeleton types are common. An elephant has an internal skeleton and uses a flexible muscular hydrostat for its trunk. Plants often combine rigid and hydrostatic support structures.

The roll for our covering gives us exoskeleton, so I'll say they have an interal skeleton (bones) as well as an outer shell. A 1 on the exoskeleton table gives a light exoskeleton - it just helps support the body, it doesn't provide any DR. Land animals always breath air. Actually, there isn't technically atmosphere on this planet, but I'll pretend the result actually gave it a very thing atmosphere for this purpose. Their temperature gets a bonus for size, air breathing, and land-dwelling, for result of standard warm-blooded (quite warm, in this case). Their growth pattern is continuous growth.

They have two sexes , and their gestation is live-bearing. A roll of 12 gives them special gestation , and a 4 on that table means cannabilistic young - the young are implanted in their parent (coin flip reveals this is the father) and they eat their way out, killing him. They have a moderate r-strategy for the reproductive strategy , having 1d6+1 young per litter and there is some care after birth.

Their primary sense is vision, giving a +4 on that roll. Vision also gets a +2 for being a carnivore. They have Telescopic vision 4. They have normal hearing with extended range, which is subsonic since they are large. They can hear (and probably make) sounds below the level of normal human hearing. Their exoskeleton gives them a penalty to the touch roll, and they have -1 DX from a generally poor sense of touch. Chasing carnivores and sexual reproduction means they have +4 to the taste/smell roll, giving them Acute Taste/Smell 4. The special Senses roll gives them Night Vision 7. Their primary communications channel is hearing, with smell as secondary.

Their intelligence is 7 (normal human is 10, chimpanzees are 6). Their mating behavior is a permanent pair-bond. Not sure how that works since the males die, but perhaps they have a particularly long gestation period or they pair up before they are able to breed. Social organization is solitary, so they hunt alone.

Now, we determine the group of mental qualities that determinds their collective species personality.

Chauvinism gives them Chauvinistic (quirk) Concentration results in Attentive (quirk) because they are chasing carnivores.
Their curiosity is normal.
Their egoism is Proud (quirk)
Empathy has +1 for chasing carnivores, -1 for solitary, resulting in normal
Their Gregariousness is at -1 for solitary, giving them Uncongenial (quirk).
Their imagination is normal
Suspicion is -1 for carnivore, -1 for large, +1 for solitary, giving them Fearlessness 1.
Playfulness is normal since solitary and high IQ cancel out.

Overall, giant tripods with a hard shell and young that eat their dad alive.