That is a addicting game. I've played it for a couple hours once. Don't know why, it's just one of those games that seem so simple, but you can't just get away from it.
This is another "puzzle" game that is fun. The first 8 levels just teach you how the game is played. I think there are 30+ levels.
3D Logic
I usually hang out on Newgrounds for the the free games on the internet.