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Stars Without Number Alien Generator
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Stars Without Number Alien Generator

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A set of simple techniques to create uniques and amazing aliens for the  Hard Sci-Fi TTRPG Stars Without Number.


You can choose among six groups of life forms:

  • Carbon Based type I
  • Carbon Based type II
  • Phosphorus Based
  • Silicon Based type I
  • Silicon Based type II
  • Sulfur Based. 


The physiology comes in eight categories:

  • Arthropoid
  • Cephalopoid
  • Fungilike
  • Humanoid
  • Insectoid
  • Plantlike
  • Reptiloid
  • Xenomorph.

Each physiology determines some of the base stats like Hit Dice, AC, Size and base saves, together with the amount of slots the creature rolls in offense, defense, sense, general, metabolism and move.


Offense includes 20 tags, they describe what kind of attack the alien can make, the damage dealt and other special attacks.


Defense includes 17 defense tags, they describe wow tough the alien is, what it employs to defend itself from threats and predators. It may also include form of passive offense techniques.


Sense includes 17 sense tags, they describe by what means the alien perceives the environment. The alien may also possess secondary senses coherent with primary one.


General includes 29 tags. A sort of default category that grants the alien peculiar abilities. It also includes abilities that provide flexibility to the alien and may increase anyone of its basic stats.


Metabolism includes 23 tags. These tags describe in principle how the internal body of the alien works.


Move includes 10 tags. How the alien move in the environment and what are its secondary method of locomotion.

Example of alien generated with the Alien Generator

Step 1 – Group 1d6) Silicon Based type I

The alien surive in an environment with ammonia and hydrocarbons atmosphere, and also the liquid it may lives is ammonia or hydrocarbons.

Step 2 – Physiology 1d8) Fungilike

The alien cells has combined to resemble a fungus. We don’t know yet more than that, but the alien has 1 base hit dice, the size can vary from tiny to medium.

It will have the following slots: Offense (1) Defense (1), Sense (1), General (2), Metabolism (1), Move (0).
Being a silicon based creature and a fungilike, we can imagine a sort of rigid or semi-rigid cellular structure. Maybe a semi-crystalline creature.

Step 3 – Offense 1d100) Sonic Burst

The creature can emit a high-frequency tone that can stun and/or slow the target. The physical damage caused by the tone is minimal, but a repeated exposition can be deadly.

The semi-crystalline creature use sound as an attack/hunting method. Maybe the alien employs sound frequencies to molecular bonds to extract nutrients from the atmosphere.

Step 4 – Defense 1d100) Egg Injection

The creature deposit eggs, or the equivalent of egg. We can imagine the alien, beside the semi-crystalline structure, possesses spikes or stinger that can infecta a target and then the eggs grow/develop/mature inside the host.

Step 5 – Sense 1d100) Tremor Sense

The creature perceive the environment vibration, both on the surface and the atmopshere.

It is possible that the range of tremor sense is higher than that proposed in the Tremor Sense entry, due to a higher density of the fluids (ammonia and hydrocarbons). The tremor sense also grants the secondary sense Smell.

Step 6 – General 1d100 x2) Improved Flexibility + Padded Paws

Improved flexibility provides the creature with the ability to move parts of its structure. However, being a semicrystalline creature, it is possible that this mobility enhance its hunting/survival techniques. The tags itself increases the # of attacks in a round by 1 and provides other bonuses.

Padded Paws would normally makes the creature more sneaky than the average in its environment. We don’t know yet if the alien can move at all, but we could interpret this tag as a sort of mimetic ability that allows the alien to change the color of its crystalline structure to match the color of its environment.

Step 7 – Metabolism 1d100) Hemocyanin

The creature seems to employ hemocyanin to aid its metabolic function. Usually hemocyanin mixes with oxygen. On earth it is a prerogative of some invertebrates like (see Octopus).

The tag provides a bonus to Exert skill checks, which may translate into a higher resistance to fluid pressures. It may also means that the copper inside the metabolism can react with ammonia to produce some energy to sustain the life form.

Step 8 – Move n/a

A fungilike creature usually does not possess move tags, unless specific combination appears. The creature only way to “move” is to expand the fungi-like colony.

The pdf also explains how to determine all the stats of the creature. In addition, every tag rolled provides the “numbers” to better define the creature stats. The example you see here is just the descriptive aspect.


Future updates will expand the various elements of the Alien Generator, which means new groups and physiologies, together with new tags.

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Discussions (2)
Customer avatar
Jesse S June 10, 2022 12:52 am UTC
Could you double check your general tags section? Both "Brain lobes" and "Carnivorous" are listed on the roll table but are missing from the subsequent pages where it should describe what those traits do.
Customer avatar
Davide T June 10, 2022 2:07 am UTC
Hello Jesse,
Thanks for the feedback.
I am proceeding right now toward the correction of both missing paragraphs.
Make sure you have flagged to receive the option for the update of the new file when it will become available.
The update may be releases this very evening or tomorrow.
Customer avatar
Davide T June 10, 2022 2:48 am UTC
Hello again Jesse,

The file of the Alien Generator - Stars Without Number compatible has been updated according to your feedback.
Please let me know of any other issue.
Customer avatar
Jesse S June 10, 2022 11:47 pm UTC
Thank you for the quick response! I love this resource, been using it a lot. One other small mistake I found. The table on page 10 says reptiles can be medium or large, but in the paragraph on page 13 says reptiles can only be small or medium.
Customer avatar
Davide T June 11, 2022 12:20 am UTC
The table has the priority. However nothing prevents you from using any size you prefer. The most important paragraph is "making connections". I am curious to know what kind of aliens have come up with.
Customer avatar
Scott C March 17, 2022 5:16 pm UTC
I've skimmed this and am very impressed. I now need to dig into it. It not only lets you roll to create a bunch of races, but has the same creation vibe as SWN, so good job.

The only thing I would love to see would be a way to make these Playable Character Races. It seems like a 1-2 page discussion appendix might do the job: As a PC, if the race is Tiny, then HP is -2 or something, and/or a table with points for each Tag, where an Alien PC race can only have a net +1 total, or if they use their Race as a Foci, they can have a net total of +2 or +3, etc.
Customer avatar
Davide T March 22, 2022 6:51 pm UTC
Hello Scott, I am answering now because I didn't check the follow discussion option.
The subject of expanding the playable races in SWN seems to be a thing that deserve attention.
I tried to include this in the alien generator, while working on it, but I don't know how to obtain a good flavor from it.
I'll be honest, you are the second person who ask me about playable races and intelligent aliens in general. I think the only way to provide a good solution would be to expand the Alien Database (free sample), and from there offer a wide range of intelligent alien races with a good array of foci.
I take the chance to ask you a question: would you like to see exotic races and "fantasy" races exported in SWN? This is my great doubt.
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File Last Updated:
June 09, 2022
This title was added to our catalog on March 12, 2022.