The Music Interactive. The website has a lot of free games to download, including a fun STAFF WARS game. You must register to download the games. I can't wait to share these with my students!
Other great games are RHYTHM DICTATION, which has the student listen to a rhythm and choose the correct sequence from the rhythms provided. You are able to choose what rhythms to include, so it is appropriate for different levels.
RHYTHM BLOCK is similar, except their patterns to choose from.
SPEED NOTE is not as exciting as Staff Wars, though it does have selectable levels.
Enjoy these fun games!