Item in as new condition. Some items may be carefully resealed for protection only. Professor Heinz Wolffs Gravity is a game of 100 set-em-up and knock-em-down puzzles all based on the laws of physics. Players construct devices from building blocks levers conduits and other parts. True to the title most puzzles are solved by harnessing the force of gravity through a rolling ball a falling block or other such event. Some puzzles have players creating contraptions of Rube Goldberg-like complexity although many have more than one solution and often the simplest works as well as any. The Wii edition of the game also includes 20 sandbox levels for player experimentation as well as four multiplayer mini-games.