A space combat mini-game & universal RPG supplement.

Why should you care?

You want this game if…

Required Materials

To play Cosmoforce, you’ll need:

Building a Ship

Your ship’s “Roster” is its character sheet. A blank roster is found here. You build a ship by filling out the roster.

The first step to building a ship is to select a class. There are three classes of vessel. Each has a number associated with it called its “Size Modifier” (“Size Mod”) which denotes generally how big the ship will be.

Class Size ModDescription
Fighter 1 A small vessel optimized for speed and maneuverability.
Cruiser 2 A heavier gun ship designed to crack large vessels at a distance.
Capital Ship3 Massive vessel designed with durability foremost in mind.

After selecting a class, choose which Systems you wish to mount on your ship. There are six universal systems available to all ships:

System Description
Armor Absorbs damage
DissipatorManages heat
Engine Moves your ship
Habitat Holds your crew
Laser Cooks enemy ships
Missile Blasts enemy ships

Each class has a special system that only it may mount.

System Class Description
AfterburnerFighterBetter Engine
Hangar CapitalCarries tiny drone ships
Railgun CruiserA very efficient cannon

To mount systems, write the name of that system in one of the ten “System Slots” on your roster. Each slot holds only one system. You can repeat systems in multiple slots to get increased effects from those systems.


When you’re satisfied with the systems you’ve mounted, calculate your ship’s mass. The formula for calculating mass is:

Mass = Size Mod x Number of mounted systems

A Fighter with four systems will have a mass of 4. A Cruiser with the same number of systems will have a mass of 8. A Capital Ship with the same amount will have a mass of 12.

While loading up with systems makes your ship more powerful, having more mass also makes it slower and easier to hit.

Crew Complement

Crew are useful for repairing your ship’s damaged systems. Without a crew, your ship is dead. Every ship gets at least 1 Crew and can have more if you mount Habitat systems.

Each Habitat system increases your ship’s crew complement by an amount equal to its size modifier.

Complement = 1 + (Size Mod x Number of mounted Habitats)

A Fighter with two Habitat systems has a complement of 3. A Cruiser with the same number of Habitats has a complement of 5 and a Capital Ship with as many has a crew complement of 7.

Start with a number of Crew Tokens equal to your Crew Complement.

Crew State

Crew tokens begin in the “heads” position to denote that they’re ready for work. When crew become hurt, flip the token over to the “tails” position.

It doesn’t matter which side of the coin you use to denote states as long as you’re clear and consistent.

Start crew tokens anywhere on your roster except on top of the system slots. Placing crew tokens on system slots has rules significance.

Initial Speed and Heat

Your ship will start at a speed proportional to the number of propulsion systems you have mounted.

Speed = 3 - Size Mod + Engines

For the purposes of this formula, a single Afterburner counts as three Engines.

Your ship will also start with a number of Heat tokens equal to the number of propulsion systems mounted. For the purposes of initial heat, Afterburners count as a single mounted Engine.

Rolling Dice

In space, precision is life but chaos is king! Correct calculations are the difference between victory and defeat. Die values represent variance in the calculations so you want them to be low.

When you roll dice, you’ll roll any number of them (from 1 to dozens) depending on the kind of roll you’re performing.

After you roll, always discard dice with values of 7 or 8. These represent energy lost to heat, human error in operations, and other inefficiencies that plague space ship operations.

Any dice that remain after discarding are called your Effective Dice. Having more Effective Dice means you’re more successful.


Dice with values of 1 are special. They represent the highest precision possible and can pay dividends. Whenever you roll a die with such a value, immediately roll an additional die and treat it as if it were part of the original roll. Extra dice can also cascade in this way, allowing you to pull in dice ad infinitum.

Rolling to Shoot

Shooting at enemy ships follows the same rolling rules described above with one addition: Smaller ships are harder to hit. Add up the values of all your effective dice. If they exceed the Mass of the ship you’re shooting at, you must discard dice until the remaining dice values fit inside the target’s mass. Dice that remain are called Hitting Dice.

If you’re shooting at a ship with a mass of 7, and you roll two effective dice, both at values of 4, they add up to 8 which exceeds the Mass of the target. You must discard one of those dice, leaving only one hit for the roll.

If you roll to shoot with a single die and it turns up 6, that die counts as a hit only if the target has a Mass of 6 or higher. Such a roll would miss outright when shooting at tiny ships with a mass of 5 or less.

Each “hit” forces the target to apply 1 damage.

Stationary Targets

If you’re shooting a ship with a speed less than 1, it’s really hard to to miss. In this case, any effective dice rolled count as hitting regardless of the target’s mass.


Battles in space take place at speeds and distances so great that Special Relativity is working against you. You can’t actually know where your enemy is, only where they were at some point in the past. Such fighting involves more guess-work and anticipation than it does careful measurements of distance and velocity. You and your enemies will be actively exploiting this aspect of physics.

For this reason, the particulars of range and placement are abstracted away into the dice rolls and statistics of each ship and the margin of error in all your calculations is never really zero.


No two ships can ever have the same speed value during combat. To resolve ties, tying ships each roll as many dice as they have working Engines. If your ship has Afterburners mounted, each one counts as three engines for the purposes of this roll. Effective Dice for this roll add 0.01 to the ship’s total speed. Repeat this roll until all ties are broken.

Combat Rounds

Combat is divided into Rounds which have two phases:

Execution Phase

During the Execution Phase, each ship has a Turn. The fastest ship takes the first turn, the second-fastest ship takes the second turn, etc.. See the Turn Actions section for a list of things that can be done on each turn.

Once every ship has taken a turn, proceed to the Aftermath Phase.

Aftermath Phase

When this phase begins, you may remove 1 Heat token from your Roster for each working Dissipator your ship has mounted.

After dissipating heat, any Heat Tokens that remain put your crew in jeopardy. Roll 1 die for each Heat Token on your Roster. Each effective die forces you to choose one of the following:

If your ship has no working Engines (all engines are damaged or destroyed), it is careening recklessly through space and risks colliding into space debris. In this case, roll as many dice as your ship’s total speed (ignoring all fractions). Each effective die forces you to apply 1 damage.

Combat Turns

At the start of your Turn, any ready Crew assigned to repair systems are now successful. Each assigned crew clears one damage mark from the system they’re working. You may relieve Crew from the repair assignment or leave them there to continue repairs.

Turn Actions

An your turn, you can take two actions. You can take two different actions or the same action twice as long as it’s not the Attack action. Available actions include:


When you attack, select a type of weapon you have mounted. You may choose to fire all or some of your weapons of that type. You can not mix weapon types during a single attack action. Roll to Shoot with as many dice as your systems call for. Each weapon system has special rules that apply to its rolls. Weapon systems are:

Hangar (Drone Strafe)

When attacking with this system, you open the hangar doors and unleash a swarm of fighter drones that beleaguer the enemy.

Roll 2 dice for every Hangar system you use. When these dice roll 1’s, they count as zeroes when compared against the target’s mass.


Shooting focused radiation at the enemy can sear through a ship’s hull and cook the squishy occupants within.

Roll 1 die for every Laser system you use. If any of those dice turn up with a value of 7 or 8, each forces you to place a Heat Token on your roster. In addition to applying the standard damage, each hitting die places a Heat Token on the target’s roster.


Missiles use gyroscopes and computers to home in on the target and detonate their explosive payload on the enemy’s hull.

Roll 3 dice for every Missile system you use. If you roll two or more dice with values of 8 in that roll, the fired Missile systems become Depleted (circle the “Depleted” word on that slot) and can’t be used again.


Long tubes of electromagnets running along the keel of your ship that propel a heavy slug at high velocity. Impact from a rail slug is devastating but aim must be precise.

Roll 1 die for every Railgun system you use. If the target vessel is slower than yours, roll 3 for every used railgun instead.

Burn Engines

When you burn engines, they generate heat. Place a number of heat tokens on your Roster equal to your ship’s Size Mod.

You may then increase or decrease your speed by an amount equal to the number of working Engine systems you choose to use. For these purposes, Afterburners count as three mounted Engines.

Conserve Energy

Thermodynamics is one of your biggest enemies in space. By taking a moment to do nothing, you generate no additional heat and give your ship’s dissipators a chance to catch up.

Roll a die for each Dissipator you use. Each effective die removes 1 Heat token from your Roster.

Heal Crew

Every Habitat system is equipped with a make-shift medical bay where Crew can get pain killers, stimulants, splints, blood transfusions and hydrated enough that working becomes possible again.

For each working Habitat you have, flip a hurt Crew Token over to the ready position.

Repair Systems

The main function of crew is to stitch, tape, weld, and bash your ship’s systems back together when inevitably wrecks them. You may assign crew to repair damaged but not destroyed systems.

When you take this action, assign any number of ready Crew to repair a single system by moving their tokens onto its slot. There they will remain until one of the following happens:

Strafe Run

The size and maneuverability of fighters make it possible to race along the hull of an enemy, roasting and blasting at it as you pass.

When you perform this action, take 1 heat then roll 2 dice for every Afterburner you use. Each effective die lets you identify a system on an enemy ship. For the rest of the turn, if that system takes damage, it immediately suffers an additional point of damage.

Damaging Systems

When you’re forced to apply damage, you are responsible for choosing which systems get damaged. Distributing the damage among your systems is part of the strategy of the game.

For each 1 damage you’re forced to apply, mark one of the check boxes on a filled system slot.


Your ship is eliminated from the game if any of the following is true:

Realism Sucks (Kind Of)

Cosmoforce is not meant to be “hard sci-fi.” In fact, we think that realism is just a crutch for sloppy game designers. However, we wanted the game to remain fun while still allowing a hard science fiction campaign to use it. That’s part of why we don’t have any “shields” or faster-than-light travel rules and why heat is one of your biggest threats.

While we encourage you to use realism as a mode of communication and not as the final arbiter of how the game should play, we hope that the framework provided in these rules can accommodate at least some small level of simulation for gaming groups that are keen on that stuff.

RPG Incorporation

If you’re using this as a supplement for an existing RPG system, you probably want your character to be part of the crew. Your character will count against the crew max as set by the ship’s habitats and can be used as crew in all the normal ways.

Remember that no matter how awesome a character is, space ships deal with mass and energy levels that are a huge deal. Just because you’ve got an epic level demigod spell caster doesn’t mean that railgun fire can’t ruin his day.

Your character is still supposed to be awesome. Rules that “hurt” normal crew don’t necessarily incapacitate your character – which means, you can take a beating and still repair systems. Your character is likely to be sporting more talents and capabilities than regular crew as well.

5th Edition Incorporation

Some people think that space ships clash with the whole D&D theme. To the contrary, space craft have been a tradition in the game since the early days of Gary Gygax. So if you’re running Queen of the Demonweb Pits and the players want to take over Lolth’s spider ship, this can help you.

When using Cosmoforce in “the world’s greatest RPG,” here are some ways that you can integrate the native mechanics:

FATE Core Incorporation

When using Cosmoforce in FATE Core, here are some examples of how to incorporate the native mechanics:

Savage Worlds Incorporation

You might assume that because the Savage Worlds Science Fiction Companion exists, there’s no reason to use Cosmoforce in the Savage Worlds system. You may be right. But if you don’t want to use the Chase rules for your space ship combat, this may service your needs well.

Here’s a list of suggestions for working in the Savage Worlds system:

Post-Ship Role-Play

If you were to be realistic (shame on you!), losing your ship would pretty much guarantee death for any inhabitants. But why outright kill players when you can torment them with a glimmer of hope instead?

When your ship is destroyed, your crew aren’t necessarily dead. Destroyed ships simply mean you can’t participate in space battles anymore. Though cinema and video games have trained us to assume all defeated space ships explode and break down to quarks, Cosmoforce makes no such assumption. It’s up to your GM/system/intuition to decide what each ship actually does when it maxes out on damage.

It’s more fun if, when your ship is destroyed, it becomes a kind of dungeon to escape. There may still be a space battle going on around you and now your characters have to don EVA suits and escape with their lives!

Here are some ideas for how the drama and tension can rise while aboard a derelict ship:


Sometimes, you don’t want to role-play. You just wanna blow the snot out of somebody. Here are the one-on-one showdown rules:

Mosh Pit

If you’ve got more than two people around, try this:

Example: With a mass budget of 30 a team can have one huge Capital Ship stacked to the brim, or two ships whose cumulative mass is 25, or three tiny ships with a total mass of 20.


You and your friends build a small fleet and do your best to survive an endless onslaught of randomly-selected threats. One person is the GM and will control the threat ships. All others are Survivors who build their own ships. Damage carries over between fights so you’re probably going to die eventually. For each fight you survive, you gain 10 points. For each slot on your roster that isn’t filled with systems, you gain an additional 5 points.

Roll a die for each ship in your group to select from the threat chart below. Remember: Ones always cascade. If you roll a 1, add another die and your fight will involve multiple threats. For every three fights you finish, add another die to the roll, thus adding more ships to the mix.


  1. Punk Striker
  2. Bargain Bin Gun-Ship
  3. Ricketty Mothership
  4. Missile Boat
  5. Parade Float
  6. Star Hammer
  7. Astrotank
  8. Baby Striker

Punk Striker

Fighter (1) - Mass: 4, Speed: 5, Complement: 1

Bargain Bin Gun-Ship

Cruiser (2) - Mass: 12, Speed: 2, Complement: 3

Ricketty Mothership

Capital Ship (3) - Mass: 21, Speed: 1, Complement: 4

Missile Boat

Fighter (1) - Mass: 10, Speed: 6, Complement: 1

Parade Float

Cruiser (2) - Mass: 20, Speed: 2, Complement: 1

Star Hammer

Capital Ship (3) - Mass: 30, Speed: 1, Complement: 1


Capital Ship (3) - Mass: 30, Speed: 1, Complement: 4

Baby Striker

Fighter (1) - Mass: 2, Speed: 5, Complement: 1

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