The Incredible Machine" for the new generation with some 3D graphical flair.
The premise is simple: get the ball into the blue "basket", even if only for a moment, by using various tools available, usually gravity. You have various planks you can connect, power to motors to "paddle", and other tricks.
You will come up with very Rube Goldberg-type machines where one thing leads to another, then another... The one above has the ball getting "scooped" up the vertical chute by that motor with winch. The scoop is nailed together by several "planks".
There are dozens of levels, all of them challenging to a degree.
This was offered for free one day on Amazon AppStore, but the developer experienced very bad experience on it, and pulled it from Amazon. You have to buy it from Android Market now.
Works GREAT on tablets!
Definitely try the lite version first!
LITE version (free)
Full Version ($1.87)