Years ago, before the d20 system hit the market, before Wizards bought TSR, TSR produced a game called SAGA. For its time, this game was fairly innovative. It had a familiar mechanic for task resolution - the familiar Ability + Random Value versus Difficulty Number that was fairly standard through the 90s and is now the default for d20-based games.
The innovative part of SAGA was the use of cards as random number generators instead of dice. There were other games that had done this before SAGA (notably Castle Falkenstein, a wonderful game), but SAGA was the first one that I played that flowed really, really well. Most of this was due to the action mechanic that required that players always be the active player in every action or counteraction, instead of alternating between the player taking an action and the GM taking an action.
SAGA came in two flavors - a fantasy version set in the world of the Dragonlance books and a super-hero version set in the Marvel Universe. Each version came with its own deck of cards, themed to the particular gameworld. The Marvel deck in particular was a lot of fun, decked out with not just suits and attributes for each card, but "Callings" to inspire you with ideas for why your hero became a hero and random events that the GM could pull as needed when the story needed a bit of oomph.
SAGA was not a perfect game. The original Dragonlance version had 8 different attributes for the player to keep track of, which slowed down play more than you might think. Each attribute also had a "skill code" associated with it that controlled things like what type of armor your character could wear, whether he could use sorcery, what kind of weapons he could use, and so on. The magic system was an on-the-fly point based system that in theory gave you a lot of flexibility with building spells, but in practice was a bit too much bookkeeping for the lightweight system.
The Marvel revision was an improvement over the original. The 8 attributes were collapsed down into only 4 to take care of. A couple of simple cardplay mechanics were added that improved play quite a bit. The Marvel system also replaced the "skill code" mechanic with a small skill list based on attributes. While an improvement overall, the skill list system was still a bit clunky compared to the rest of the system.
