Abbadon The Thirteen Seals is a Tabletop Role Playing Game (TTRPG) that uses a full standard 54-card deck, including Jokers, to determine the outcome of a Character's actions.

Abbadon is a dark fantasy game that draws inspiration from Diablo and Darkest Dungeon. It takes place in the world of Haven, wherein the Players take on the roles of ill-fated and grim heroes who face perilous odds - hordes of undead, monsters, and demons - to stave off the growing darkness and stop the return of the Lord of Demons, Abbadon.

The system itself uses Target Numbers that players much play their playing cards each action to achieve. The number of cards they draw per action is depending on a few things such as skill and attribute ranks, weapon and item traits or sometimes penalties due to enemy abilities or conditions.

The book itself contains all the rules needed to play, the four character archetypes players can choose from with their massive array of skills and items. There is a brief history of the world of Haven and information on a few locations within it. A massive bestiary with over 60 advesaries, mechanics for altering and powering these advesaries up to maintain the challenge as well as the 13 Demon Lords which serve as major antagonists for campaigns and a way of measuring the difficulty level. There are also mechanics for randomly generating dungeons and magical items and treasure.