A pentomino is a five-square puzzle piece. If you took five squares, and laid them against each other, edge to edge, then that would be a pentomino. There are exactly twelve different ways you can arrange five squares. In the original puzzle, the task was to create interesting patterns using the pieces. This version of Pentominoes is played on a 10" x 10" board ruled into 100 squares. (Solomon W. Golomb's original design for a pentomino game featured an 8x8 grid of 64 squares.) Each player has one set of Pentominoes and these are placed anywhere on the board in turn. The object of the game is not to make patterns, but to place pentominoes on the board in such a way that the last player cannot place a shape on the board. Limits to placement: 1. A vacant space of at least five squares must be left after placing a piece on the board. 2. The winning player may place some of his remaining pieces in the vacant spaces to score double points for one and triple points for two. The rules add a tip: It is advisable to try to reserve a space in the shape of one of your pieces after your opponent has played that shape.