pydance is a dancing game written in Python, formerly named pyDDR. The idea is simple. There's a floor mat with arrows, and the game scrolls arrows up the screen to the beat while playing a song. When the arrows reach the top of the screen (not sooner and not later), the player hits the corresponding arrow on the pad, and given that it's hit on time with the beat, points are scored. Based on how well the dance is put together, s/he is graded at the end of the song. Both keyboard and mat play are supported.