In case you have any spare time on your hands that you want to have totally eradicated by a very addictive flash game, may I present: Red Remover. All you do is bust the red shapes, keeping the green ones onscreen. But it gets harder and harder, with multiple planes of gravity, and then there’s a second round that’s pretty ridiculous. You can *feel* yourself getting smarter while you play.

Here’s a tip: Look at the name of each level name before you start; it’s helpful and will become even more helpful in the second round. I am proud to say I completed the whole game at par* in “hard” mode, without any hints. I am ashamed to say that I wasted all my spare time for an entire weekend doing so.
Thanks to Emmanuel for the tip.

* Except Level 44, on which I could not do in less than 2 over par.
But I was below par for two other levels so I’m counting it.

Oh, and here’s another fun flash game – Totem.