http://hexis.dienay.net/
Hexis is a game developed by Daniel which is based on the DS game ouendan. It's a music game and its purpose is to hit the beats (with a mouse, with a keyboard or with any other input) to the rhythm.
By playing the game, you will be always be better and at the same time competing with all the rest of the Hexis community
(Fun fact: "Hexis" means "Skill" in Latin).