Are you up for a real challenge? Or maybe just a humbling experience?

Planarity has just what you need. It features mind-bending planar graphs. Planar graphs are diagrams that can be drawn with no intersecting lines. You’ll need your thinking cap on to play this game.

Planarity displays planar graphs that have been jumbled up. You must move the points so that the lines which join them don't intersect.

Sure, it sounds easy, and the first few levels aren't too bad. But then the going gets tough -- really tough. Fortunately, the Web site owner took down the high scores, so it isn't that humbling!

Click here: http://www.planarity.net/