Over the weekend I introduced the card game Donsol ( popularized by @rek and @neauoire ) to my friend on a road trip. Lots of fun!

The way we played it, I would draw the rooms and improvise a role-playing campaign to accompany the game as we went along. Monsters included "Cracker Barrel manager" and "post-partum depression". The simplicity of the actual mechanics of the game -- deck of cards and two numbers -- make it easy to tack on any story you want.

Recommend for improvisers or RPG fans!