How to Play Cortex Prime

Hello fellow nerds! I wanted to take a minute to break down one of my favorite TTRPGs: Cortex Prime. Cortex Prime is a toolkit system, which is both a strength and a weakness of the system. On the one hand, it can cover a huge variety of genres with all of its mods, on the other, it makes learning the game a bit intimidating, especially if all you have is the Cortex Prime core rulebook. Now, there are some ready to play games that use Cortex. Currently the only one in print from the Cortex team at direwolf is Tales of Xadia, but you may also be able to find used copies of Firefly, Smallville, Leverage, and Marvel Heroic Roleplaying. Additionally, there are third party Cortex Games that can be found on itch, such as Cortex Lite, Lifted, Keystone and the Cortex Xine.

Characters

Let’s start with what makes up your characters in cortex. Player characters are made of traits, organized within trait sets. Attributes and Skills are probably the trait sets you will be drawn to if you’re coming from many of the more popular games, and they do pretty much what you expect. However, some games are less about what your character is capable of, and are more interested in what they believe in, and their connections to other people. These games might use trait sets such as affiliations, values, and relationships. You might also have powers or abilities if you want your characters to feel powerful or extra distinct.

Each Trait within a trait set is defined by a die value, ranging from d4 to d12. What traits are within a trait set will vary from game to game. You could easily have an attribute trait set with strength, dexterity, constitution, etc. but it may be more thematic to have Mental, Physical, and Social as the attributes. It all comes down to what is important to the game that you’re playing. Trait sets like values and relationships commonly use something called a trait statement where you describe your belief or specific relationship. You can also challenge a trait statement for a bonus when your character is questioning their belief in that statement, but you must change the statement afterwords.

Distinctions are a special trait set that is mandatory. Each distinction is something unique about your character, and is by default rated at a d8, with the option to lower it to a d4 in order to gain a plot point, which is the meta-currency of Cortex. Distinctions can be anything, but many games will guide you somewhat with prompts and tables. It’s common to have one distinction for where you’re from, another for your profession, and a third that’s some sort of unique quirk of your character.

While there is no limit to the number of trait sets that make up a character, the minimum is 3, one of which must be distinctions. These are called your prime sets and are the core of your character.

Taking Action

When you want to do something where failure could be interesting, you’re going to want to make a roll. To roll, you start with your prime sets, and select the most applicable trait from each set and add that die to your die pool. You will end up with at least 3 dice, one from each prime set, and potentially more if you have traits from non-prime sets that are applicable.

The GM will also assemble a pool of dice as the opposition. If going up against a major NPC they will likely have a full character sheet of their own and the opposition dice pool will be made from that NPCs trait sets. Minor obstacles will likely not have the same amount of traits and the GM will have something like “d8 commoner” and then judge the difficulty of what you’re trying to do in order to fill out the rest of the dice pool, up to 3 dice. There are also mods to change how the GM creates the opposing pool, such as the doom pool and crisis pools.

Both you and the GM will roll your dice pools, each of you will first set all 1s to the side, these are hitches, which we’ll get to later. from the remaining dice, you will select 2 and add them to create your result, and select one of the remaining dice to be your effect die. The number rolled on the effect die doesn’t matter, only the size of the die. Your goal is to roll higher than the GM in order to succeed, and the size of the effect die determines how successful you are. a d4 effect die you are barely scraping by, but a d12 is a tremendous success.

Rolls usually come in two varieties, tests and contests. Tests are a one-off challenge, and Contests represent more of a back and forth. In a test, you simply roll once and whoever comes out on top narrates the resolution of that conflict. In a contest, whoever is initiating the conflict rolls first, setting the stakes. Then the other party will roll to beat them. If the second party succeeds, they have set the new stakes, and the first party has a chance to roll again, possibly with different stats if they decide to change up their approach. At any point, one party can concede, or if they fail to beat the opposing party’s roll they will be taken out for the rest of the scene.

There are, of course, mods that can introduce more complexity such as turn orders and action based resolution. However, for the most part in Cortex things are resolved in whatever way makes the most sense narratively.

Consequences

So what happens if you fail your test, or concede a contest? Usually it means taking a complication equal to the size of the opposing effect die, or stepping up an existing complication to a larger die size.

A complication is essentially a temporary negative trait on your character. When you fail a test or concede a contest, you will get a complication as a result, and then in future tests the opposing pool can use this complication by adding the complication die to their dice pool.

Complications can be resolved by taking an appropriate action within the narrative to deal with it, and may or may not require a roll depending on the situation. A complication can be worsened by continuing to fail tests. If the opposing effect die is higher than your current complication die, that effect die will be your new complication die. If the effect die is smaller, your complication is stepped up one die size. If it would go beyond a d12 you are taken out and cannot act for the rest of the scene.

There are other consequence mods as well, such as stress and trauma, the doom pool, and crisis pools. Stress is essentially pre-defined complications, so when something negative happens it will go to one of your stress tracks, if you get taken out as you would with a complication. You will also gain trauma, which will likely take much longer to get rid of, though the specific rules vary from game to game.

The doom pool replaces the opposition dice pool and can also replace complications and stress, or be used in conjunction with them. The doom pool represents the tension of ever raising stakes, and will grow as you fail.

Crisis pools are a doom pool mod that represent more specific threats, such as a fire or an angry mob, instead of the general feeling of dread associated with the doom pool.

Hitches, Plot Points, and SFX

I mentioned both hitches and plot points previously, so let’s go over what they are. A hitch is whenever a 1 is rolled. If a player rolls a 1, the GM can activate this hitch by giving the player a plot point, at which point they can give the player a complication. The player can negate this by spending a plot point of their own.

Players can similarly spend a plot point to activate a GM hitch, giving the players an opportunity of some kind, or applying a complication to an NPC.

Plot points can also be used in other ways. Usually this is to activate some sort of SFX, or a special ability related to a trait. We’ve mentioned one SFX already, which is that distinctions can be lowered to a d4 in order to gain a plot point. You may also have SFX that allow you to step up a die, add an additional die to your die pool or result, or use a trait that normally would not be used in this situation.

Outside of SFX, plot points can be used by players to add something to the scene, this could be something like a d6 crowbar asset that they happen to find on a crate nearby, or to establish a relationship to an NPC.

Character Progression

Like many games, Cortex allows you to advance your character. What this looks like is going to depend on the specific game, but you can generally expect to unlock new SFX, step up trait die, and add a new trait to non-prime sets like assets and powers.

One of the ways cortex does progression is session records, where you make a note about each session and you can then turn that in for some form of advancement that’s relevant to what happened in that session. There’s also milestones, where each character can gain XP based on their own specific goals, and can spend that XP to advance. Tales of Xadia uses the growth pool, where you add to the growth pool by recovering from stress/complications, and you use this pool to roll against a trait, advancing that trait if you succeed.

I think that about covers the core ideas of how to play cortex as a player. If you’re wanting to run a game, then a lot more will probably go into it, especially if you’re only working with the Cortex Prime core rulebook and don’t have Tales of Xadia or any of the kickstarter setting spotlights. I’ll probably do another writeup of how to hack cortex to create the game you want to play in the future. In the meantime, I’m happy to answer any cortex related questions, and I also recommend the cortex discord and subreddit for places to learn more about cortex

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