Each player has a set of 12 different pentominoes (for those who don't know what those are, think Tetris pieces with 5 squares instead of 4) to place on a 10 x 10 grid.
Each player alternates placing a piece on the grid. There must never be a closed-off area of 4 squares or less. The last player to play a legal move wins.
One of the solitaire ways to play is to try to completely fill up the 10 x 10 grid using any 20 of the 24 pieces.
The game was reissued with a larger board and 3 and 4 player variants under the name Universe.