rpgs mothership horror sci-fi


Note: This document is a work in progress. As I make changes to the game, they’ll be reflected here (literally every time I save!). There will be disorganized and scattered notes and half-finished thoughts. If you’re looking for the most recent complete draft, you can find that here. Also, if you want to read more about Mothership, you can find all my blog posts about it here.

Character Creation

Welcome to Mothership! A sci-fi horror RPG where you and your crew try to survive in the most inhospitable environment in the universe - outer space! You’ll excavate dangerous ruined space hulks, explore strange unknown worlds, exterminate hostile aliens, and examine the horrors that encroach on your every move. Let’s get started!

Mothership Character SheetMothership Character Sheet

You can actually design your character right from the character sheet above. All the steps are printed on the sheet. You can see an example of a completely filled out sheet below. But if you need a little bit more information, or find the character sheet confusing, here’s what you do:

An example filled-out character sheet for Lilith.An example filled-out character sheet for Lilith.

1.1 Roll 6d10 for each stat.

Mothership uses d10s for everything, so grab and handful and get rolling. You’ll want to roll 6d10 (roll six 10-sided dice and add them up) and then record the results in order starting with strength, then speed, intellect, and finally combat. You’ll roll stats between 6-60, averaging around 30 each.

Read more about Stats

1.2 Pick a Class and note their starting Saves.

Here you’ll pick one of the four basic classes in Mothership:

Put a √ or X in the circle above the class you pick and then fill in the starting saves in the boxes provided (they’re written in light grey in the box for you already, so you don’t have to fill these out right now if you want to wait until they change).

The starting saves are reason, psyche, body, and armor. These saves are like resistances to different kinds of trauma, danger, or damage.

Read more about Saves

Additionally, if you follow the arrows at the bottom of each class’ column, you’ll see that each class alters your starting stats a little bit. (For example: the Teamster gives +5 to both strength and speed). Go ahead and change your starting stats.

1.3 Take note of your Skills

Each class comes pre-loaded with a couple skills, go ahead and put a √ next to your class’ starting package and then feel free to add a skill or two that you think rounds out your character. Skills give you a bonus to performing certain actions.

Read more about Skills

1.4 Take note of what happens when your class Panics

Each class behaves differently under stress and the special rules for that are listed on the character sheet. Give a √ to your class’ Panic rules.

Read more about Panic

1.5 Pick a starting Loadout

There are four different starting equipment packages to choose from. These are here for convenience so that new PCs don’t have to spend a lot of time shopping before the game begins. They should feel free to add a couple pieces of equipment that they think they may need as well. Fill out your PCs stress (starts at 0), resolve (starts at 1), and max health (x2 strength), give them a name (and rank or title if they have one) and you’re good to go!

Basic Rules

For the most part, Mothership plays like many other RPGs. The GM creates a scenario or location for the PCs to explore and interact with and the game is what happens during that play. Here are a few important things to keep in mind while playing.

2.1 Rolling the Dice

Mothership uses standard d10s for all of its rolls, though it uses them in 3 different ways:

The two different dice we use in MothershipThe two different dice we use in Mothership

2.2 Stats and Stat Checks

Whenever a PC wants to do something and the price for failure is high, then they must roll under the appropriate stat on d%, otherwise they fail. PCs have four stats, which are:

There are a few things that can modify this roll, namely skills, situational advantages & disadvantages, and critical hits & critical failures.

2.3 Situational Advantages & Disadvantages

Whenever a PC is making a stat check and they have a situational advantage, they make a d% roll as normal, but instead of rolling 1d10, they roll 2d10 and pick the best of the two (usually the lowest). Some examples of advantages are:

Additionally, the GM will adjudicate on a case by case basis whether certain in game actions or effects will confer advantage onto a PC for a check.

Example: Abel is trying to open a long since rusted shut airlock on a derelict space hulk. He’s using a crowbar and is getting assistance from Lilith. The GM decides this is a Strength Check with advantage due to the assistance, so Abel tries to roll under his Strength score of 36. He rolls d% with advantage, meaning the dice show 20, 40, and 03. Abel takes the lower of the two d10s, the 20, and adds the 03 for a total result of 23 - success!

Disadvantage works much the same way as advantage. The PC will roll 2d10 and pick the worst of the two (usually the highest). Some examples of situational disadvantages are:

Characters can’t have advantage and disadvantage at the same time. If you have both, they cancel out.

Example: Lilith is trying to run to an airlock before it closes automatically. The ship is twisting and turning and debris is falling in every direction. The GM rules that this will be a Speed check with disadvantage. Lilith rolls d% with disadvantage against her Speed 42. She rolls a 50, 60, and 05. Both are failures, but taking the highest roll here isn’t the worst roll - taking the 55 (a critical failure) is! Lilith won’t make it to the airlock, and worse, it sounds like she’s about to get hit by some floating debris!

3.1 Critical Hits & Failures

In that last example, we showed you what a critical failure was before explaining it to illustrate how sometimes the highest number in a disadvantage roll isn’t always the worse number. So, let’s back up and explain what a critical hit or failure even is.

Anytime the result of a stat check is doubles (meaning the same number on the d10 and the d10, i.e. 55, 22, 99), then that roll is what we call a critical. If the roll was a success, it is now a critical hit. The PC has exceedingly succeeded at the task at hand. If the result was a failure, however, it’s now a critical failure, a catastrophe, and not only does the PC fail at the task, but may incur some other penalty, complication, or even damage as a result. A roll of 00 is always a critical success and a roll of 99 is always a critical failure.

3.2 Opposed Checks

When two parties are in direct competition they make an opposed check, that is they make stat checks as usual and whoever rolls highest without going over their own stat is the winner. Critical Success will beat a regular success (even if the critical success is a lower roll). Additionally a critical failure will give success to the other party (even on a failed check). For everything else, like ties or dual failures, re-roll!

Opposed checks do not have to involve the same stat - or even stats at all. A basic case would be a race to see who gets to a gun first - both parties make an opposed speed check. But you could also have a PC trying to trick a creature into attacking in the wrong direct by making an opposed Intellect vs. Combat check (or maybe even Spped vs. Combat). Or its even possible have an android trying to win an argument against a human by making an opposed intellect vs. reason (save) check.

3.3 Saves

Every PC has four saves: reason, psyche, body, and armor. Saves are not rolls the PC makes willingly (like when they use their strength to open a door), PCs make saves when something bad might happen to them, and they need to find out whether they can resist it.

To make a save, a PC just needs to roll a d% equal to or under their Save score (just like with a stat check). Failure usually means damage either to a PCs health or a Panic Roll. As usual, critical Hits and Failures still apply. Additionally, whenever a PC fails a Save (other than Armor Saves), they can increase their failed save score by 2% permanently (up to a maximum of 85). The trauma makes them tougher.

Read the descriptions of each of the [Saves


Skills are the accumulated knowledge, craft, techniques, and training a PC possesses. Every class comes with a few basic skills to start off with. You can gain more skills through levelling up.

Read more about Levelling Up

4.1 The Benefits of Skills

The major thing skills offer is advantage when your PC is trying to make a check. A scientist trying to perform a dificult surgery will have a much easier time making their Intellect check with a skill like surgery than will a Teamster with no relevant skills. Whether a Marine with a skill like First Aid would get the same benefit is up to the GMs discretion.

4.2 A Non-Comprehensive List of Possible Skills

GMs and PCs are encouraged to come up with their own skills through play and developing their own dark corner of the galaxy, but here are some to start with:


Combat is Mothership is incredibly deadly, and usually best avoided all together in favor of running and hiding. But in those dire situations when you must fight for your life, here’s what you do:

5.1 How to handle Surprise

Sometimes the various creatures, horrors, and denizens of long forgotten spacecraft will sneak up on the PCs before making themselves known - when this happens, PCs should make a psyche save, or become so surprised that they are unable to act for one round. When the PCs are attempting to surprise an enemy, that enemy must make an instinct save to not be surprised.

Read more about Instinct

5.2 Who goes first?

After checking for surprise, determine the order of play. All the PCs make a speed check. Those who pass can act before the enemies do, those who fail, however, act after. This repeats every round.

5.3 How long is a Turn?

Combat takes place in both rounds and turns. A turn is focused on one individual PC, NPC, or group of NPCs. A round is the time it takes for every character to take a turn. Each round is equal to roughly ten seconds of real time, with every character’s turn happening roughly within that time but in turn order (as opposed to all at once). Meaning someone who is killed before their turn, would not get to act on their turn.

5.4 What can I do on my turn?

When its your turn, tell the GM what you’d like for your character to do, what you imagine them doing in this situation.The GM will tell you if you can get all of that done in one turn, or if it would take multiple turns to accomplish all of what you want.

Generally, PCs can accomplish two significant actions during their turn. Examples of significant are (but not limited to):

Insignificant actions are things like talking, or taking cover (as part of a move action), looking around, etc. The GM will ultimately decide what counts as a significant or insignificant action given the context of each specific situation.

5.5 How do I attack?

Attacking is a specific kind of significant action, performed by rolling an opposed check. The attacker makes a combat check against the defender’s armor save. If the attacker succeeds, they roll a number of damage dice equal to the d10 rolled in their combat check (meaning if they rolled a 43, they’d get to roll 4 dice of whatever type their weapon specifies). Each weapon will have a specific type of dice they roll for damage (some will roll d10s, while powerful weapons will roll d10s.)

5.6 Do I get a bonus from cover?

Characters behind cover of any kind gain advantage on their armor saves. Characters who spend both actions only defending themselves in melee combat should generally receive advantage on their armor saves, since they are not trying to mount an offense. Final discretion is left to the GM.

I’ve got the rest in print layout, but I’m still working on transferring it all over to the website. So stay tuned!

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