Each player has a set of 12 different pentominoes 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. Online Play BoardSpace (real-time, AI option) Mobile Apps Boardspace.net local multiplayer or online, IOS Boardspace.net local multiplayer or online, Android