Mushroom Farm Revolution. It's like Desktop Tower Defense, only better. That's right. Who knew it could get any more exciting than DTD? But it has.
A good way to waste time and/or something to do when you're bored and want some strategy to keep you occupied. The farthest I've gotten so far is 33/45. Can you beat that?
EDIT: I tried out a new strategy that got me to wave 60/60 on world 5 before I died. It was easy peasy up through that wave though.