Homebrew system first developed in 1998 and used in a number of campaigns for our South Bend, IN group. The highly adaptable mechanics have been applied to:
A Swashbucklers mini-campaign;
A Weird Modern campaign heavily influenced by Unknown Armies (which ran for three years);
Libri Vidicos, an ongoing Steampunk/Hogwarts campaign (ongoing and heading into year three);
A Changeling the Lost reworking (going into its second year);
A High Fantasy Campaign taking inspiration from Glorantha (just begun).
Action Cards is an abstract, low-detail, high-trust RPG system. While characters still use an essentially random system to determine results of conflicts, they can influence those results through narrative, tailor their possible results to their character, and develop a customized character sheet.
Players build their characters out of two things: a character sheet- which has a handful of basic details- and a deck of homemade cards. A player distributes successes and failures across those cards, adds cards unique to the character, and through experience tunes abilities. The GM has his own universal deck used for opposed tests and resolution.
While each version has had some tinkering and new systems added to fit with the genre, the core mechanics remain the same throughout. The game aims to give players ownership over the narrative and a parallel feeling of ownership over their results through the use of the cards.