It's the Tetris, you see.
I had a serious Tetris problem back in the early '90s when work slowed to a crawl, pending contract renewals and what-not. We were literally told not to work; I asked my boss, "So, what, I'm supposed to play Tetris all day?" He said, "That's all right with me." So I did.
Admittedly, you can find other, much better versions of Tetris, and some of them are probably even free, too. But I didn't go looking for them because I didn't need the temptation. Now I'll get to see how good my self-discipline really is.
(*) by which, of course, I really mean, "Thanks, Jonah!"