Cortex Prime
Core RulebookBest For
GMs who want to build a custom system from modular parts: homebrew designers, genre-mixers, and groups tired of forcing their stories into a pre-built framework.
Core Mechanic
Assemble a dice pool from trait sets (attributes, skills, relationships, etc.) rated d4–d12. Roll the pool, keep the two highest for your total vs. opposition, then choose an Effect Die from the remainder to determine magnitude. Plot Points let players add dice, activate abilities, or alter the narrative. Every mechanical element is a swappable mod.
Resolution is roll-and-keep: build a dice pool from trait sets rated d4 to d12, keep the two highest, and pick an effect die from the rest. The depth is modular. SFX, plot points, assets, and complications all bolt onto that core, and the exact mix is built per game.
- Free to tryQuickstartA free starter you can actually play
- Get it nowSold newIn print or as a legal PDF
- ✓IndexFind any rule by page number
- ✓GM guidanceA chapter on how to run the game
- ✓Examples of playRules shown in action at the table
- ✓Quick referenceCheat sheet or summary tables
- ✓Cross-referencesRules point to each other by page
5 of 5 book tools found in the core book
Highlights
Highly modular: 18+ mods for core rules alone, clear writing with worked examples, Plot Point economy creates dynamic give-and-take, powered well-known licensed games (Marvel Heroic, Firefly, Leverage)
Considerations
The game is not playable out of the box and requires significant GM assembly. There is a steep learning curve to understand which mods fit your game. Every roll involves choosing which dice to keep plus an Effect Die, which slows resolution.
Rules license Cortex Creator License
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