This is probably one of the most fun rhythm games I have ever found. Think Guitar Hero or DDR on steroids.
You use your own music to play the game or choose from one of several songs that the developers switch out occasionally. There are online score boards and 6 different ways to play. You can also have a friend list and compare scores and achievements.
The game play is awesome. You pilot a ship using either the mouse, arrow keys, or WSAD keys from left to right collecting blocks. Get three or more blocks of the same color to connect and you get extra points. Don't over fill a column though or you won't be able to pick up blocks for a while and you'll lose points!
It does cost $10 to download but there is a free trial.
WEBSITEJust check out some Youtube videos. This game is intense.
((I control the leader board for the castle crashers soundtrack...))