Each player sits on opposites of a large silouhette head with empty space in the middle. Each player draws cubes from a bag (two colored cubes glued together, making more of a rectangle--much like three-dimensional short Tetris pieces) and places their piece in the empty space in the head (the empty space is two cubes deep). They can orient the blocks in any fashion they like.
Play continues until one player fills their side (later rules contradict this and that usually dictates whether someone will like the game or not). Then players score by tallying up the different chunks of color on their side of the head (larger areas of the same color score more).
At least in the first edition, the head is mighty wobbly.