Genesys is built around a custom set of color-coded dice with special symbols on them:
- Ability Dice (green, 8-sided): The player typically rolls a number of ability dice equal to their ability score. Ability dice have successes and advantages marked on them.
- Proficiency Dice (yellow, 12-sided): The player replaces ability dice with proficiency dice equal to their skill level. Proficiency dice have successes, advantages, and triumphs marked on them; a proficiency die has better odds of successes and advantages than an ability die.
- Boost Dice (blue, 6-sided): Boost dice are added to a roll to mark advantages that improve the player's chance of success. Boost dice have successes and advantages marked on them, and have less dramatic effects on the roll than ability dice.
- Difficulty Dice (purple, 8-sided): A number of difficulty dice is added to the roll to indicate the difficulty of the action being attempted. Difficulty dice have failures and threats marked on them.
- Challenge Dice (red, 12-sided): Effects that upgrade difficulty dice convert them to challenge dice. Challenge dice have failures, threats, and despairs marked on them.
- Setback Dice (black, 6-sided): Setback dice are added to a roll to mark disadvantages. Setback dice have failures and threats marked on them.
The dice are effectively the same as the dice in the Star Wars RPG, except without the Force Die, and with different symbols used. The symbols for success and failure are similar, but the others are very different; if the players know the symbol mapping, the dice can be used interchangeably.
Successes and failures cancel each other out, as do advantages and threats. The net results are then totaled up; for a roll to succeed, there must be at least one un-cancelled success. Net advantages and threats are used to determine side-effects of the roll. Triumphs count as successes with a significant advantage; despairs count as failures with significant threats. Triumphs and despairs do not completely cancel each other out; the success and failure parts are cancelled normally, but the extra effects will remain. A phone app for iOS and Android is available to handle dice rolling if the physical dice aren't available; in addition, the app for the Star Wars Roleplaying Game can be used if the symbol mapping is known.
A central mechanic for Genesys is the Story Point pool. The players share one pool, and the GM gets another. The pools start with one story point per player in the player pool, and one point in the GM pool. Players can spend their points to upgrade one ability die to a proficiency die in their dice pool, or upgrade one difficulty die to a challenge die in an NPC's pool. Similarly, the GM can use points to upgrade ability dice in an NPC's pool or difficulty dice in a PC's pool. Story points can also be used to activate special abilities and talents, or to give the players a spot of luck - "Good thing we remembered to bring space suits!" Spent points go into the opposite pool after the action is completed. (So, a point spent by a PC goes into the GM's pool, and vice versa.) This replaces the Destiny Pool from the Star Wars game.
Three official settings have been released by Fantasy Flight, all based on other FFG games:
- Realms of Terrinoth: A fantasy setting used in Descent: Journeys in the Dark and other games.
- Shadow of the Beanstalk: A science fiction/cyberpunk setting used in Android and its related games.
- Secrets of the Crucible: A science fantasy setting used in Keyforge.
In addition, FFG has made the "Genesys Foundry" available through DriveThruRPG as a way to allow fan-created works to be published. Many settings across multiple genres are available for purchase.
Tropes found in Genesys include:
- Character Class System: Character templates are provided in the core book and each setting book, which gives initial statistics, starting skills, and initial talents.
- Critical Hit: Called Critical Injuries, they are typically obtained by rolling enough advantages to match the critical rating of the weapon; any triumph in a successful attack is enough to trigger a critical injury. They then cause short-term or long-term negative effects on the character in addition to the damage of the hit.
- Damage Reduction: The character's brawn and armor combine to create their Soak value, which is the amount of damage absorbed from each hit.
- Hit Points: Wounds and Strain, where wound points track actual damage and strain points track stun, exhaustion, and expended effort.
- Luck Manipulation Mechanic: The Story Points are explicitly meant for this sort of use.
- Non-Combat EXP: The recommended way to award XP is a fixed number at the end of the session, about 20 XP for a 3-5 hour session, adjusted for length of session and how quickly the GM wants the players to improve.
- Point Build System: Characters improve by spending XP to improve their characteristics and skills, and to purchase talents.
- The Six Stats: Agility, Brawn, Cunning, Intellect, Presence, and Willpower - basically a one-to-one mapping to the stock six.
- Universal System: The core rulebook includes short sections for fantasy, steampunk, weird war, modern day, science fiction, and space opera; in addition, it gives notes on tone for horror, intrigue, mystery, pulp, romance and drama, and superheroes.