Othello is a
board game, also known as
Reversi. Kind of
interesting. The idea of the game is to change all playing pieces on the board to your color. The players put pieces on the board; all opponent's pieces between the new piece and your other pieces, in straight lines, change colors to your color. A player must place the piece on place that will result in at least one piece's color change. (For full rules, see
Reversi.)
It came with Windows 3.0 and earlier - too bad Microsoft removed it from Windows 3.1, replacing it with Minesweeper... I have also seen versions of it for DOS, TI-85 and of course several versions for Linux. Yahoo! and many other sites also have a networked, multi-player Java applet versions.