This song always brings back memories of what was a pretty good chunk of my childhood. Me being a complete asshole anonymous kid on the internet, PKing people with my walls of flame. MUAHAHAHAHA. I had ears coming out of every pocket on my godly plate of the whale.
I'm very impressed with that software. It would be a great learning tool for people wanting to play piano.
Link from the description: http://synthesiagame.com/
Basically it's Rock Band but with a full keyboard. You download the midi and play it, with an option to change the speed.
You wouldn't learn how to read sheet music, but you'd be able to play the songs no problem.