StepMania

Ever heard of a video game called Dance Dance Revolution? That game in the arcades where you stomp on plexiglass arrows which makes you look like a retard or someone with rage issues taking out his/her/whatever anger on the dance pad?

Well this post isn't about that. It's about its clone called StepMania.

StepMania (or SM) is basically an open-source clone of Dance Dance Revolution. The difference between DDR and SM is that:

1. You can add songs, themes, etc. to SM.
2. It's free (and open-source, which means you can make modifications to the code to add features like some people did).

SM can played with either a dance pad (through the use of special adapters) or the keyboard. Simfiles (songs and step files for SM) are designed for either pad or keyboard play.

Let's get to the screenshots. Here's the mode select screen:
the style select screen:
the difficulty select screen :

the music select screen:
and the main game (it's on AutoPlay, obviously):
SM is also capable of playing different game modes than DDR. Here's a screenshot of SM in Pump It Up mode:

An extra feature is that you can edit steps of songs you like (or songs you made)

More info can be found on the StepMania website (also includes program downloads and older versions)

Some websites for SM Stuff:
Zenius-i vanisher.com
StepManiaThings
StepMania MEDIA (registration required, in Spanish)
bemanistyle.com (registration required)