This is pretty great to come up with games out of playing your idea.
A downloadable game
scaffold is half a joke and half dead serious. i believe strongly that the best way to design games is to get to the table asap and that the best way to do that is to have a scaffold -- a bare minimum functioning game to wrap around a piece of something you want to test. that is scaffold: an absolute minimum of role-playing game that you can use to prop up something you want to test.
i am not providing you with a game. i am not even providing you with a tool to make games. i am taking away one more excuse to avoid getting your idea to a table and playing it.