CRAM is an impartial two-player game. The board consists of a rectangle ruled into squares with some random squares removed. This Demonstration uses a 4×4 board with 4 black squares removed. Players (you and the computer) take turns placing dominoes on the empty (white) squares; dominoes can be placed either vertically or horizontally. The last player to place a domino wins. The first player's dominoes are colored blue and the second player's dominoes red to make it easier to follow the play. If it is possible for you to win, you will be so informed before you start.
To play, click in the area between two squares; a pale highlight indicates where your domino will be placed.
The theory of two-person impartial games along with its implementation in Mathematica is covered in the book by Robert Cowen and John Kennedy, Discovering Mathematics with Mathematica, which is currently being revised to be compatible with Mathematica 6.