Reversi and Othello variants

Reversi has fewer real variants than most classic games, because there is so little to change. Four rules, one board, two colours. The interesting variants alter exactly one of those and see what happens.

Standard Othello, the baseline

Everything else on this page is measured against this. An 8x8 board, four discs fixed in the centre before play, black first, a move is legal only if it flips something, and most discs wins.

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This is what the World Othello Federation's rules describe, what every tournament uses and what the board on this site plays. The federation's rules contain no variant section at all, so treat everything below as informal. The official rules.

Anti-Othello: fewest discs wins

Also called reversed Othello or anti-Reversi. Every rule about placing and flipping stays the same. You still have to play a move that flips at least one disc, you still pass when you cannot, and the game still ends when neither side can move. Only the final comparison flips: the player with fewer discs wins.

That single change turns the strategy inside out. Corners, the most valuable squares in normal Othello, become dangerous, because a corner anchors discs that can never be flipped back off you. X-squares, normally poison, become useful.

What does not invert is mobility. Running out of legal moves is bad in both games, because a player with no moves has to sit and watch while the opponent shapes the board. The full anti-Othello guide, including a position where this site's engine turns down a free corner.

Free-start Reversi, the Victorian original

Before Othello fixed the opening, Reversi began on a completely empty board. Players took turns placing their first two discs anywhere in the four central squares, and only then did normal play start. Some rule sets also required those first four discs to be placed without flipping anything.

The arrangement below is legal under those rules and impossible in modern Othello: black in a vertical pair on d4 and d5, white opposite on e4 and e5.

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Fixing the start is the change that made competitive Othello possible. Once every game begins identically, openings can be named, catalogued and studied, which is what the openings index is for. Free-start Reversi is worth playing once for the historical curiosity and then never again. Reversi vs Othello, rule by rule.

Small boards: 4x4 and 6x6

Shrink the board and you get a shorter, sharper game, set up the same way with four discs crossed in the middle. Both common small sizes have been solved outright by computer, and in both the second player wins with perfect play, which is a useful thing to know before you agree to go first.

The 4x4 game is over in a dozen moves and is mostly a curiosity. The 6x6 game is genuinely playable and is a good teaching size, because corners come into play almost immediately and a beginner can see the shape of the whole game in ten minutes. More on how these were solved.

Bigger boards: 10x10 and other shapes

Going the other way gives 10x10, sometimes called Grand Othello, with 100 squares and the same four crossed discs in the middle. The online strategy site PlayStrategy runs it as a supported variant.

A bigger board mostly means more mobility for longer. Games run around half again as long, the middle of the board takes many more moves to fill, and corners stay irrelevant until much later. The strategic ideas do not change, they just arrive later.

There are also cut-corner shapes. Octagon Othello is a 10x10 board with three squares removed from each corner, leaving 88 squares and eight short diagonal edges instead of four sharp corners. It is a real change rather than a size change, because it multiplies the number of squares that behave like corners.

Rolit: four players

Standard Reversi cannot take a third player, because a disc has two faces. Rolit, published by Goliath in 1997, gets around that by replacing discs with balls that have four coloured faces. You roll a ball to change its colour instead of flipping it.

Rolit plays with two, three or four players on an 8x8 board. The capture rule is Othello's, applied to whichever colour you are. The board fills to 64 balls and the player with the most of their own colour wins. With four players it becomes a much looser, more political game, since anyone can undo anyone else's work and the leader is a target.

Rolit is worth knowing about because it is the only well distributed answer to the question people always ask, which is whether three or four people can play. The honest answer for Reversi itself is no, and no house rule fixes it: a disc has two faces, and that is the whole game.

Rule tweaks you will meet in casual play

• Placement without flipping. Some house rules let a player place a disc anywhere when they have no flipping move, instead of passing. This makes the game much easier for beginners and much less interesting. The real passing rule.
• Empty squares to the winner. Not a variant, an official rule. If a game ends with empty squares, they are awarded to the winner, so 33-29 with two blanks is scored 35-29. Scoring in full.
• Brightwell Quotient. A tournament tiebreak that adds a share of your opponents' results to your own, used to separate players on equal match points. It affects standings, not play.
• Timed play. Tournament Othello uses a clock, usually 30 minutes per player for the whole game. Running out loses.

Which variant should you actually try?

Sources

• Reversi on Wikipedia, for the free-start original, anti-Reversi and the Brightwell Quotient.
• Computer Othello, for the 4x4 and 6x6 results.
• Rolit on BoardGameGeek, for the 1997 Goliath edition.
• Grand Othello (10x10) on PlayStrategy.
• World Othello Federation official rules, which cover the standard game only.