Planarity

Beware, before visiting this page make sure you have a few hours to spare. Once you start you're not going to stop: play Planarity. I've reached level 10 a few times. Some folks at work have gone to level 18, which I find really hard to believe...

Update:Looks like this game does not play on Mac. Oh well. You Mac users are spared. Me? I'm playing way too much. Would you believe level 19?