Reversi - Complete Guide

Reversi has a contested history involving two 19th-century Englishmen. Lewis Waterman of London is often credited with inventing the game in 1883, but John W. Mollett claimed he invented it earlier under the name "The Game of Annexation." The dispute was never fully resolved, but the name "Reversi" stuck, and the game was sold in England by various companies.

Reversi remained moderately popular for nearly a century until Japanese salesman Goro Hasegawa revitalized it in 1971. Working with game company Tsukuda Original, Hasegawa made minor rule changes (standardizing the starting position) and marketed the game as "Othello," named after Shakespeare's play—"a minute to learn, a lifetime to master" became the tagline. The reference to Shakespeare's play about the conflict between the Moor Othello and the white Desdemona reflected the black and white discs flipping between sides.

Othello became a phenomenon in Japan and quickly spread worldwide. The World Othello Championship has been held annually since 1977 (with few exceptions). Japanese players dominated early competitions, but the game has become truly international with champions from many countries.

The game's elegant simplicity and strategic depth made it a natural fit for computers. Early game-playing programs mastered Othello before chess. The game is now "weakly solved"—with perfect play from both sides, the game is a draw (or possibly a slight advantage for Black or White depending on the opening).

Reversi/Othello is played on an 8x8 board with 64 identical discs that are white on one side and black on the other. The game begins with four discs placed in the center: two white and two black, positioned diagonally.

Objective: Have more discs of your color showing when the game ends. The game ends when neither player can make a legal move (usually when the board is full).

Legal Moves: You must place your disc where it "outflanks" at least one opponent disc. Outflanking means your new disc and an existing disc of your color surround a continuous line (horizontal, vertical, or diagonal) of opponent discs with no gaps.

Flipping: After placing your disc, all outflanked opponent discs are flipped to your color. You must flip all discs in all directions where outflanking occurs—you cannot choose to flip only some.

Passing: If you have no legal move, you must pass. Your opponent then plays again. If neither player can move, the game ends (even if empty squares remain).

Winning: When the game ends, count the discs. The player with more discs showing their color wins. If both have 32, the game is a draw.

Opening Position (Othello): The standard Othello opening has the four center discs arranged with the two same-colored discs on a diagonal. In Reversi's historical rules, players could place their first two discs anywhere in the center four squares.

Tournament Rules: Competitive play typically uses chess clocks with time limits. The standard Othello board is green with the discs fitting into indentations. Tournament boards and discs have specific size requirements.

Reversi strategy appears simple but contains profound depth. Disc count matters least in the early and middle game—position is everything.

Corners Are King: Corners cannot be flipped once captured. They provide stable anchors for building unflippable discs along edges. Prioritize moves that gain corners or prevent your opponent from getting them.

Avoid X-Squares and C-Squares: X-squares are diagonally adjacent to corners; C-squares are orthogonally adjacent. Playing there often gives your opponent the corner. In general, don't play adjacent to corners until you must.

Edge Strategy: Edges are stable once anchored to a corner but dangerous otherwise. "Unbalanced edges" (odd number of discs) are harder to approach safely than "balanced edges." Learn to analyze edge positions carefully.

Mobility: Having more legal moves than your opponent is often more important than having more discs. If your opponent runs out of moves, they must pass, giving you extra turns. Maximize your mobility while minimizing theirs.

Frontier Discs: Discs adjacent to empty squares are "frontier discs"—they can be flipped. Discs completely surrounded by occupied squares cannot be immediately threatened. Minimize your frontier while maximizing your opponent's.

Parity: In the endgame, the player who makes the last move in each empty region has an advantage. Understanding "parity" (odd/even empty square regions) is crucial for endgame success.

Common Patterns: Learn named openings (Tiger, Rose, Heath, etc.) and their standard responses. Study "wedge" techniques for creating stable disc formations. Understand "swindles"—positions that appear bad but have hidden resources.

Endgame Counting: In the final 10-15 moves, counting becomes possible. Calculate which moves lead to the highest disc count. Practice exact counting in simple positions before tackling complex ones.

While Reversi/Othello has a standard form, several variations exist:

Anti-Reversi: The goal is to have fewer discs at the game's end. Completely changes the strategy—you must force your opponent to take discs.

Reversi with Holes: The board has some squares blocked or removed, creating obstacles and changing strategic patterns.

Random Reversi: Starting positions are randomized rather than the standard four-disc center. Tests pure tactical ability.

3D Othello: Played on a 4x4x4 cube. Flipping extends in three dimensions. Much more complex to visualize.

Rolit: A four-player version by Goliath Games, played on a cross-shaped board. Up to four colors compete, making alliances and strategies more complex.

Tanbo: Each player plays two colors (both their own and one shared). Points are scored based on your primary color's count, adding partnership dynamics.

Grand Othello: Played on a 10x10 board. Longer games with more strategic possibilities.

Speed Othello: Very short time controls (bullet or blitz style). Tests pattern recognition and quick calculation.

Correspondence Othello: Played over days or weeks with no time pressure. Allows deep analysis of positions.