Quickdraw

Quickdraw is a GM-less, 2-player mini game that only requires a deck of playing cards and a timer. 

You and a friend play dueling cowboys, squaring off with six-shooters.  It's a game of bluffing and quick strategy, made to last only 5-10 minutes per match.

Built, no joke, because I had Big Iron by Marty Robbins stuck in my head one night.