A downloadable ttrpg mechanics system

ver. Mar 31, 2023

COSMIC Toolkit For Role Playing Games is a set of mechanics for playing or creating a role-playing game. 

COSMIC stands for:

  • Cooperative
  • Open
  • Short
  • Modular
  • Independent
  • Collaborative

It is free and open to everyone under the Anti-Capitalist Attribution Cooperative License.

You may use this to create a new game or salvage mechanics and ideas from this. What you can't do is create racist, bigoted, transphobic content based on anything you find here.

Table of Contents

Click the links below to navigate to each section.

Character Creation

A character has:

  • Name, Pronouns, a short description;
  • 3 Approaches, Direct, Discrete, and Device.
  • 5 Specialization;
  • 1 Unique Trait;
  • Levels.

A character does not have:

  • Race, alignment, intelligence scores, or any other bioessentialist, racist tropes in their creation or mechanics.

Defining Approaches

Direct, Discrete, and Device are abstractions of 3 ways to tackle a problem. Roll 3d6 for each Approach.

When applying it to your game or setting, make sure to reflavour it.

  • Direct - doing things directly, in the open, honestly, or forcefully;
  • Discrete- doing things subtly, carefully, thoughtfully, or insightfully;
  • Device - doing things with tools, currency, or contacts.

Design Guidance

When coming up with your own game or adapting this system to your setting, you are encouraged to rename and resignify these Approaches to something setting-appropriate.

By all means, don't need to map your own Approaches to these, or even keep the same number. You could have 3 wildly different approaches that overlap or ignore the ones above or 4+ Approaches.

A dungeon-crawling fantasy game could use Fight, Avoid, and Item. Or maybe, a solo version of the game could have Fighter, Cleric, Mage, and Thief for Approaches, and have a single Character Sheet cover a whole party.

Choosing Specializations

Choose 5 things you think this character is really good at in 2 or 3 words, such as hacking computers, detecting magic, guile, stealth, or horseback combat.

Create a Unique Trait

Create a specific detail such as an ability, a skill, a magical item, a power, and so on.


This system is GM agnostic, but I will refer to a GM as shorthand for whoever has the priority or is in the role of creating the fiction and responding to other players' actions at any time.

The GM will lay out a situation and each player decides what their characters say or do. When the outcome of an action is in question, determine whether it is opposed or unopposed, then roll the dice.

Rolling Dice

When trying an unopposed task the GM determines the Approach.  Roll 1d20. A result below that Approach is a hit. A result equal to that Approach is an extraordinary hit. If any Specialization applies, roll 2d20 and pick the lowest number. Either dice counts towards an extraordinary hit.

When trying a directly opposed task, both sides roll 1d20. Each player ignores a result below their own score and uses that score number instead. The higher number is a hit. If both results are equal, it's a Draw.

If there are one or more Conditions that affect your actions directly, the GM might ask you to roll 2d20 and keep the worst result. If you are getting the benefit of a skill or something else at the same time you are getting the drawback of a Condition or something else, they all cancel out.

Hits and Misses

On a hit, ask the GM a yes/no question and they must answer YES. The question must make sense with the fiction.

  • Do I break into the system?
  • Do I avoid the patrolling guard?
  • Does the spy give up something useful for my mission?

On an extraordinary hit, the GM adds AND to their answer.

  • When you hack the mainframe you break into their system, AND you found a loophole that makes you untraceable too;
  • You avoid the patrolling guard AND when he thinks no one is there, he looses a brick from the wall to hide something;
  • The spy spills the beans about the conspiracy to murder the baron, AND because he is terrified of your threats he adds in a secret about the council.

On a Draw, the challenger asks the question and the GM adds BUT to their answer.

  • You win against the house champion BUT she is suspicious you cheated;
  • You convince the guard you are just a passer-by BUT he wants to see your identification;
  • The spy spills the beans BUT they manage to stall just about enough for the countess to spot you both together.

On a miss, the GM may offer a consequence, a drawback, a cost, or escalate a problem. You may choose to take a Condition and earn 1XP instead.

Conditions and Trauma

Every time you take a Condition, write a short sentence describing it, then roll 1d20. If you roll over the number of Conditions you have, good for you.

Condition examples:

  • My arm is broken;
  • I am too tired and sleep deprived;
  • I am too angry at myself;

If you roll below, you are Out. Choose a Condition and make it permanent as Trauma, then erase the others. That character may return the next time the group finds a moment of respite.

Trauma examples:

  • I never fully recovered the movement of my fingers on the left hand;
  • I never get a full night's rest because of nightmares and anxiety;
  • I have self-loathing and I can't believe anyone likes me.

When you have as many Traumas as levels, retire your character, whether they give up the life, die, or pass on the torch to a new character as a non-player character. You must retire your character in this scene or at the start of the next scene.

At level up, you may treat your Trauma. A treated Trauma becomes a Scar and remains with you. It may still interfere with your rolls, but it won't count against your levels.

Scar examples:

  • I never fully recovered the movement of my fingers on the left hand, but I got a piece of prosthetics that helps me hold things;
  • I never get a full night's rest because of nightmares and anxiety, but a therapist taught me some techniques to rest the body, even if the mind won't fully;
  • I have self-loathing and I can't believe anyone likes me, but these people stick around for some reason and I can't let them down.

Unique Traits

You may use your unique trait once per session to avoid a roll or clear a Condition. Any roll you avoid counts as a hit.

Roll 1d20. If you roll below your level you can do it once more this session.

Level Up

At the end of the session, you may level up if you have at least twice as many XP as your level. If you don't, you get 1XP. After you level up, reset your XP to 0.

When you Level Up, choose 1:

  • Learn a new Specialization;
  • Increase an Approach by 1;
  • Treat a Scar.

Also, roll 1d20. If you roll below half of your levels rounded down, you may add a new Unique Trait.

Non-Player Characters

Creating non-player characters does not require much. Should an NPC need stats, give them a Skill score and a Specialization or more. This should only be necessary when negotiating your needs against that character's needs.

If an NPC or more, like a group, band, or faction, are more relevant and impose significant tension to the narrative, you might turn them into a challenge instead.


Any form of relevant opposition or obstacle to the characters counts as a challenge.

  • A band of pirates;
  • A difficult stretch of land for traveling;
  • Court politics.

Challenges have a skill score, any number of Specializations, and Resistances. Each Resistances are how and why that Challenge opposes the characters.

  • A band of pirates

    • Skill 12;
    • Specializations: close-quarters combat, intimidation;
    • Resistances: iron-fisted captain, criminals, greater numbers, yeehaw;
  • A difficult stretch of land for traveling;

    • Skill 7;
    • Specializations: none;
    • Resistances: uneven topography, large predators, short time;
  • Court politics

    • Skill 14;
    • Specializations: etiquette, blackmail, espionage, name-dropping
    • Resistances: ambitions, deep pockets, favours.

Overcoming challenges

To overcome a challenge you must break a challenge's Resistances. To break a Resistance, once you find yourself in the appropriate fictional position, you may make an opposed roll. On a hit, the GM will choose whether your actions broke a challenge's Resistance, inflicted a Condition, or both.

Foundations of Play

This is a set of guides for designing and running games around the players and the themes they want to engage and that the setting might encourage.

Foundations of Play is inspired by Skeleton World and PUSH.


Every game has a concept, a top-level idea that should summarise what the game is about and evoke how to play it in players.

The concept doesn't need to be anything fancy. Even with just a couple of sentences, you can imply factions, historical events, and a major plot point.


Once you good a concept, list what major themes this game is about. Your themes will remind you where to go to when you are stuck, and help set expectations for all players involved.

Your list of themes doesn't need to be comprehensive but should cover the main and most sensible ones.


The pillars of play are certain boundaries expected to be always true in the game and the setting.

As an example, look at the Pillars of fantasypunk:

  • heroic fantasy: the world is alive and vibrant, and it doesn’t revolve around you;
  • wondrous and mundane: magic exists and it is wondrous and wild, althout it is hardly world breaking, if at all;
  • humanity is relative: people are complicated, diverse, and often conflicted but are mostly kind and willing to do good;
  • monstrosity is relative: the real monsters are those who stand against happiness, love and the freedom of being, usually by choice or complacency;
  • no hat fits all: no individuals, communities, religions or cultures are single-minded, unilateral or exclusive.

Although the pillars of play touch the fiction, they are directed at the players, informing them what limits there are and expanding upon the Themes established.


The Agenda is a set of goals that help push the game toward its themes and pillars.

A good Agenda is aware of what tropes, genres, and cliches should be encouraged to hit the game concept and help guide players towards it. You should cover at least the basics below:

  • Play to find out what happens;
  • Deliver the world according to its concept and pillars;
  • Deliver action in line with the themes;
  • Engage Calibration Procedures (safety tools) liberally.

Improve and grow this agenda according to the game you want to play.


If the Agenda represents the goals of the characters and players in the game, Principles represent just how to go about achieving these goals.

I would say that the list below should cover most situations:

  • sprinkle evocative details;
  • name everyone, make everyone human;
  • create tension, not plots;
  • address yourself to the characters, not the players;
  • be a fan of the player characters;
  • ask provocative questions and build on the answers.

You should improve and change this list according to the game you are going for.

Individual Agenda and Principles

Player characters can have individual sets of Agendas and Principles that add to the game's core. These Agendas and Principles are great for pushing characters towards their own goals, creating subplots and story arcs, and even helping players bring them to life.

Rule Expanded: End of Session

If characters have individual Agendas or Principles, at the end of the session, each player character gets +1 XP if they engaged those during the session.

Optional Rules: Fickle Sciences

Fickle Sciences represent the use of esoteric knowledge that push the boundaries of what is thought possible. In fantasy settings we often call them magic, while in sci-fi settings we usually call them technology.

If you choose to use such mechanics, they differentiate from Approaches in scope: approaches cover things that could be normally done as established. For example, most people can yell at a bear, some might even scare it away. But not everyone can send it flying with a shout or communicate with it telepathically, at least not your average human.

Once there is a sense of what is internally consistent in your setting, Fickle Sciences can push those boundaries, or undo them altogether.

Fickle Sciences mechanics are based on Heroic Chord/Harmony Drive by Peach Garden Games. Or at least what stuck with me from that fantastic system and its magic mechanics.

Design Guidance

Fickle Sciences also allow for individuals to influence others, or create mechanisms of coercion, by allowing certain individuals to withhold knowledge that others can't access and, forming social systems around who gets to know what. Even if most or all can access these abilities, only a few might be able to actually understand its intricacies.  

Whether Fickle Sciences are common place or knowledge that is hard to access makes a difference in how societies are formed and relations are maintained.

Personal Words

When creating a character, each character has a set of 6 Personal Words. Call them Power Words, Gadgetry, or something else appropriate. In science fantasy settings those might mean the same thing.

Location Words

When bringing characters into a scene, offer 6 Location Words. Those might be resources, technologies, emotions, aesthetics, or something else. In case of doubt, pick about half of them related to the Place, and the other half related to a Theme.

Iara is a healer apprentice who knows these Personal Words: mend, soothe, find, bone, blood, sleep.
She arrives at the Grand Waterfalls, where the Local Words are: water, flow, fall, myst, ghost, cold

Using Fickle Sciences

When using their magic, technology, and any other science, a character chooses a pair of Words, one Personal and one Local.

Describe how these words combine to create an effect or provoke an outcome. Decide how it changes the environment, gives you an advantage, or empowers you to an impossible task.

You may make up to 3 pairs of Words and you cannot repeat a Personal Word. The more Words you use, the more specific, effective, and wondrous the effect created.

After that, roll 1d6. If you roll under the number of Words used at the time, cross out one of the Personal Words used and describe how you lost access to it, whether its magical conduit is broken, its device is defective, or something else.

You may choose instead to take a Condition and cross out a Local Word. Describe how you broke, tainted, distorted something, or made it inaccessible, dangerous, or forbidden, or something else.

Iara found someone hurt by a tree. She realizes a hunter was gravely wounded and is bleeding out, there is almost no pulse. She decides it is worth trying to save them, and begins an intricate procedure if healing.

 She pairs Blood, and Flow, Find and Ghost, hoping to bring the hunter back to the world of living and guiding the blood to remain in their body.

Iara feels dizzy for a moment and realizes that in healing this hunter, her own spirit is being weakened. She must choose whether to give up some of her tools of practice (personal words), or let her spirit become ill by severing her ties with the environment (take a Condition and cross out a Local word).

Gaining and Recovering Personal Words

When you level up, choose whether you wish to recover a Word or gain a new one.

To recover a Word, roll 1d20. If your roll a number equal to or below the number of Words you still have, you may recover one you crossed out.

To gain a new Word, roll 1d20. If you roll over twice as many words as you know, including Words that are crossed out, you may gain a new Word.

Optional Rules: Challenge Pile

Determine the rank of a challenge from 1 to 5, then roll that many dice.

The player trying to overcome that challenge piles the dice and reads the side of the pile facing her, plus the side facing up on the die at the top.

Roll 1d20, and reroll once if you roll under your approach score and keep the highest roll. Compare the result with the result from the bottom die facing you.

If you beat that number, then add the die on top. If you beat the sum of both, add the next one, and so on. Stop when the result of your roll won't beat the next die.

If you beat the side of all dice on the pile, plus the top, the challenge is clear. If you beat any number of dice but not the top, check the top result to find out what is the escalation.

Reduce the challenge rank by as many dice as you beat, then decide whether anyone is gonna try again.


  1. Reduce the Rank by one;
  2. Reduce the rank by one if you take a Condition;
  3. take a Condition unless another character decides to take a condition;
  4. take a Conditio;
  5. increase the rank by one for the next try unless a character takes a Condition;
  6. increase the rank by one for the next try.

Optional Rules: Scarcity

When you need to abstract elements such as wealth, durability, supplies, and so on, you can use this procedure.

For the purpose of these rules, I'll call all of the above Resources.

Your Resource pool is a number of d6.

Whenever that Resource is at stake, spend any number of d6 from your pool. Roll all of them and keep the highest.

  • 1-4: you get the result desired from spending your resource. You can Push your roll by rolling +1d6 (not from your pool).
  • 5-6: same as above, but instead of spending all dice, spend only 1.
  • 7+: there is a problem.

An alternate, I'd say more costly alternate is this:

5-6: same as 1-4 but you spend 1 less die.

Design Guidance

Design Advice: scarcity rules are empty when they exist just for the sake of making the game harder for players. Personally, I think scarcity is one of the most material abstractions of time. You spend or lose something as time goes by, as you persist, and struggle. What could make any sort of scarcity rule more interesting is how to replenish or preserve your Resource if that is possible at all.

Optional Rules: Collaborative Narrative Tools

Add the rules to a game when you would like to influence the fiction established from outside of the Characters of the game.

They are meant to allow a collaborative approach to worldbuilding and to the conversation, while still providing a minigame.

You may replace dice for tokens, making small adjustments where needed.

These procedures are inspired by Finding Styles and Co-op Dice Mechanics.

Personal and Collective Pools

At the start of the session, each player adds 1d6 to their Personal Pool for every player present. If the game includes a GM as a player, they do so too.

The Collective Pool keeps all dice players spend from their Personal Pool.

At the end of the session, both Pools are reset to 0.

Making a Proposal

When you make a Proposal to create a new location, relationship, supporting character, fictional position, or any other element, or when you want to elaborate or change, one that already exists, describe it to the others and take a die from your Personal Pool.

Each other player takes a die from their own Personal Pool and gives it to you as long as they agree with your Proposal.

If any player withholds their die, ask them "what should be different if I don't roll a 6?". The players who withheld their dice will answer and you roll all of the dice collected. If any dice comes up as 6, your Proposal passes as you described, otherwise, take the counter-proposals into account.

All dice you received are dumped into the Collective Pool. When you run out of dice, replenish your Personal Pool with dice from the Collective Pool.

Making an Invite

When you invite the group to collaborate on an element of the narrative, ask the table about a location, relationship, supporting character, fictional position, or any other element. Avoid Yes/No questions.

Give a die from your personal pool to the player who answers the question. You may suggest a change to their answer. Give them another Personal Die if they accept it.

Deus Ex Machina

Whenever any player wants to avoid disaster, they may take any number of dice from the Collective Pool, roll them all, and add or reduce their total to another roll during an action.

If the result of the roll changes to your benefit describe how something from outside your influence changed the narrative in a most dramatic fashion.

Otherwise, describe how you got out of the frying pan and into the fire.

All dice spent are permanently removed until the next session.

Optional Rules: Becoming

These rules are designed for games and settings where the player characters "were born yesterday", like clones waking up adults and barely with any past, newly created beings, individuals who somehow lost access to most of their past memories, and so on.

These rules are inspired by Araukana Media's Nibiru.

The Self Pool

This pool gains points that characters may spend to gain pieces of who they Become.

We will use the words Self and Becoming for the sake of detailing these procedures. I encourage you to replace them in your game (unless they fit, of course). Some ideas:

  • Memory;
  • Personality;
  • Recollection;
  • Self;
  • Pieces.

Defining Truths

When the outcome of the fiction is in question, before you roll, you can spend Self and write down a new Specialisation, Unique Trait, or Scar. Write a short description of a truth about that character that they just learned about, remembered, or developed that is related to it.

Note that gaining a Specialisation allows you to improve your roll, and gaining a new Unique Trait allows you to bypass it completely. On the other hand, Trauma will negatively impact your roll.

Convenient Memory

Spend 1 Self to add a new Specialisation. Describe how you gain it.

Found Powers

Spend 3 Self to gain a new Unique Trait. Describe how it manifests at that moment.

Triggering Trauma

Write a new Trauma to gain 1 Self.

Rule Expanded: Level Up

Include an option at Level Up:

  • Increase self by 1.

Optional Rules: Origins

This is a set of prompts for creating or expanding cultures and kith within a setting with some depth, hopefully avoiding the curse of the planet of hats, or the racist, bioessentialist trappings a lot of fantasy games fall into.

By collaboratively answering these prompts, the group at the table will have generated a bunch of locations and cultures with particular, unique traits.

The Culture and Kith Worksheet is inspired by and expanded upon SabreCat's Cultures and Kith..

The Worksheet

  1. My name is (name).

  2. My people are known as: (self-referential name of the community)

  3. Which others may know as (a common form or two for other people to refer to you).

  4. We are: (type of community, a village, a city, etc)

  5. Which is known for (Unique or abundant feature or resource)

  6. And for (Cultural trait, historical event, achievement, form of organizing)

  7. People tend to think of us as (Cultural or personality trait)

  8. Which is just a stereotype. I feel I am more (Personal trait) than most of my kin.

  9. My (Ancestors, parents) were/are (kith)

  10. I've inherited from them the extraordinary ability of (fantastical feature)

  11. and also (another fantastical feature)

  12. People with my heritage are often (Any number of features, physical and cosmetic)

  13. But you can tell me apart from most by my (Distinctive physical feature or features).

  14. At home, we are (numerous, few, hidden, travelers)

  15. Among many (2 or 3 numerous other kith)

  16. with some (2 or 3 less numerous other kith)

  17. which give our people (cultural or practical quirks and adaptations ),

  18. but sometimes (tensions and challenges).

  19. Back where I am from, we often eat (yummies)

  20. wear (fabrics, colours, shapes, patterns, etc)

  21. and our language(s) is/are (types of sound, cadence, spoken, gestures, etc)

  22. We have a tradition of (Regional practice) which I (do faithfully, refuse to do, do differently…)


The tricky part in implementing this procedure is fluidity. I wouldn't want it to feel like you are writing a school paper.

On the other hand, given that the other mechanics are quite light, perhaps we can get away with it.

That said, there are ways in which these prompts interact with other mechanics.

As an example, in a game where characters are expected to relearn, rebuild, or even create who they are, you may want to present these prompts when they meet someone from their culture or kin, or when they gain memories of pieces of their selves.

Design Guidance: I highly recommend that this worksheet is competed by all players as a group, going over each paragraph and telling the others about their choices.


You may bring this worksheet to players as a separate sheet to fill in or in the back of the character sheet.

The method I lean towards the most is to embed this in the front of the page together with other elements and fields.

This would prove even more interesting if players could fill in the fields with different colours for quick identification.

Additional Prompts

You may create prompts that are specific to the genre and setting you are playing in.

Some, like the prompts below, invite players to create a kind of short backstory for their characters:

  • what trades have you learned and why?
  • what skills did you pick up thanks to it?
  • what unlikely skills did you have to pick up for it?
  • what unrelated skills did you manage to learn in spite of it?

The prompts below seem to imply that things went wrong and the characters may be in trouble:

  • why did you leave home?
  • how did you end up here?
  • what follows you from there that you are trying to escape?

Other prompts may push players towards defining and creating the supporting cast, or their wants, needs, and drives.


Recommended Mechanics, CERAMIC/MOSAIC Strict and other rules
COSMIC Free TTRPG Mechanics Mar-31-23.pdf 130 kB
COSMIC Free TTRPG Mechanics Mar-31-23.md 27 kB
COSMIC Free TTRPG Mechanics Mar-31-23.docx 26 kB
COSMIC at PrintFriendly.com

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(1 edit) (+1)

Fantastic work, Gabe. This is really excellent.

Thank you!!! I am quite prod of this!


I love this, it is going to help me flesh out the idea brewing in my head. It is so simple it is pure genius 

I appreciate the comment! Please remeber to drop me a link to what you make, i would love to see it!


I really enjoy the three Approaches! My love of alliteration leads me to suggest as alternative terms - Direct, Discrete, Device.

you know what! this is fantastic and I would like to update to these terms! that ok by you?


Yep, go ahead and use them! This will be my small contribution to a cool ruleset :)

(1 edit)

Thank you! It is done and I though I had replied to you about it before :)


clarification on the phrasing used to explain directly opposed tasks:
do u mean that players/characters must roll under their stat and higher than the oppositions roll?

quite the contrary:

when you make opposite rolls, the higher roll wins

if either side rolls below their own approach score, they use their approach score instead of the dice result.

so in an opposed roll, if my approach score is 10 and I roll a 7, I'll use 10 instead


"Each player ignores a result below their own score and uses that score number instead."

With your explanation in-hand, this line in the rules now makes more sense, but on first read it wasn't clear to me. It might be helpful to use language closer to what you wrote in the comment above.

This is a subtly brilliant mechanic by setting a floor for the character based on their natural ability in that approach, but still allowing the opponent to get lucky and roll higher.

thank you! I will try to clarify the text there!


This is fantastic!

thank you!