Reversi

How to play Reversi

Reversi is played on an 8×8 board with discs that are black on one side and white on the other. Black moves first, then the players take turns.

1. Trap discs to make a move. Place a disc of your colour so that one or more of your opponent's discs lie in a straight line between it and another of your discs, across, up and down or diagonally.
2. Turn them over. Every trapped disc flips to your colour. One move can trap discs in several directions at once.
3. Pass only when you must. If you have no move that traps a disc, you pass. If you have one, you have to play.
4. Count at the end. When neither player can move, usually because the board is full, the player with more discs wins.

The dots on the board show where the player to move can play. The full Reversi rules, with diagrams, cover passing and scoring in detail.

Playing against the computer

• Easy looks one move ahead and makes a random move about a third of the time. A good level for learning the rules.
• Medium looks three moves ahead and knows that corners are valuable and that the squares next to them are dangerous.
• Hard searches as deep as it can in under a second, values having more moves than you, and plays the last 12 empty squares perfectly when it has time to work them all out.

Choose Black to move first or White to let the computer start. Hint asks the Hard level for a move, and Undo takes back your last move and the computer's reply. Your wins and losses at each level are kept on this device.

Three tips for your first games

• Take the corners. A disc in a corner can never be turned over.
• Stay off the squares next to an empty corner. A disc on one of them often hands your opponent that corner.
• Do not grab discs early. Having fewer discs in the middle of the game usually means your opponent has fewer moves. The Reversi strategy guide explains why.

Reversi and Othello

Reversi comes from England: two Englishmen, Lewis Waterman and John W. Mollett, each claimed to have invented it in 1883, and it was popular there by the end of the 19th century. Othello is a version patented in Japan in 1971 by Goro Hasegawa, with a fixed starting position, and Othello is a trademark; this site has no connection with its owners. The game here uses that standard start, as most Reversi games do today, so if you know Othello you already know how to play.

More two-player games against the computer: Four in a Row and Mancala.