Publisher Advertisement While dominoes are made by joining two squares together, pentominoes are made by joining five squares. There are twelve, each named after the letter it resembles. To win you must fit them together to form a larger, 60-square shape, such as a 6 x 10 rectangle -- something like a jigsaw puzzle. Unlike jigsaw pieces, however, pentominoes can be flipped over as well as rotated. When you see that you have fallen into error you may remove pieces at will and try them elsewhere. Sounds easy? Sure is is -- up until the last couple of pieces! An endless fascination for the dedicated puzzler. Top-notch graphics and sound effects.