A Foosball Table half filled with water. The spinning players feet barely touch the water's calm surface on which the ball floats.
You can choose to play calmly, in which case the water will be minimally disturbed as the ball moves across its surface, or you can make waves and mayhem. I'm not even sure that it would be much of a "game", but I'm equally sure that it would be a lot of fun.
Variations: Ball does not float, but table still half filled with water. Water replaced with liquid of a heavier viscosity.-- xenzag, Oct 02 2009random, halfbakery