Crazy Machines is a puzzle game where you have to solve contraptions. It is very similar to "The Incredible Machine"
If you think logically you should have no problems completing all the puzzles, but when you get bored or stuck you can always make your own. With that option you can build anything you like with all the parts there are.
I was surprised about the good graphics and physics engine, everything looks so real. Too bad its not 3D, but that would be disastrous for the gameplay of course.
I strongly recommend to turn of the "professors comments" because it gets very irritating. Enjoy this game, and don't get too addicted!