Reversi (Othello)

Reversi (also known as Othello, the trademarked modern version) is the 2-player strategy game where you flip discs by flanking them. Invented in 1880s England, with both Lewis Waterman and John Mollett claiming it, then reworked as Othello by Goro Hasegawa and launched in Japan in 1973, Reversi has become a worldwide tournament game with computer programs that vastly exceed human master play. The premise: place a disc so a line of opponent discs is flanked between your new disc and an existing one of yours; all flanked discs flip to your colour.

How to play

• 8×8 board. Start with 4 discs in the centre: 2 black + 2 white in diagonal pattern.
• Black plays first. Against the CPU you are Black; choose Easy, Medium or Hard, or switch to 2 Players for pass-and-play on one screen.
• Golden dots mark your legal moves, and the Hint button highlights a suggested move.
• Place a disc such that you flank a continuous line of opponent discs (vertically, horizontally, or diagonally) between your new disc and an existing one of your colour.
• All flanked opponent discs flip to your colour.
• If you can’t make a legal move (one that flips at least one disc), your turn is passed automatically.
• Game ends when neither player can move.
• Most discs on the board wins.

Beginner strategy

• Corners are gold. Corner discs can never be flipped. Owning a corner is a massive structural advantage.
• Avoid X-squares. The four squares diagonally adjacent to corners (positions [1,1], [1,6], [6,1], [6,6]) often give opponent corner access. Avoid early.
• Mobility beats material. Don’t grab discs just because you can. If a play leaves you with one move and opponent with many, you’ve lost mobility.
• Edge play matters. Stable edge discs (especially long lines reaching corners) are permanent.
• Don’t over-extend early. Early game, fewer discs = more flexibility.

Intermediate strategy

• Stability hierarchy. Corner discs are permanently stable. Edge discs in long lines reaching corners are stable. Most interior discs can still be flipped.
• The “wedge” attack. When opponent occupies an edge with gaps, you can force them off by wedging discs in the gaps.
• Tempo and forced moves. Sometimes you make an obviously “good” move only to force opponent into a “bad” reply. Tempo manipulation matters.
• End-game arithmetic. Late game, every disc matters. Plan exact disc counts to ensure parity.
• Forced passes. If you can force opponent to pass (no legal move), you get an extra turn.

Advanced strategy

• Computer-perfect play. Top Othello engines (Edax, Logistello) play at superhuman level, and in 2023 a computer analysis reported that 8×8 Othello is a draw with perfect play.
• The 6×6 variant is solved. Joel Feinstein showed in 1993 that 6×6 Othello is a win for the second player with perfect play.
• Long-term parity. Final move advantage. Plan to make the last move on the final empty square.
• The “perfect game” target. Players strive for “wipeout” (opponent has 0 discs at end) or maximum-margin wins.
• Opening theory. Like Chess, Reversi has named openings: Brightwell, Diagonal, Perpendicular, etc.

Reversi vs Othello

• Reversi (1880s): the original. Various rule variations existed.
• Othello (1973): Goro Hasegawa’s standardized version, sold under the Othello trademark, fixed the modern starting position and rules.
• Differences: Modern Othello starts with the 4 centre discs in a fixed diagonal pattern. Reversi historically allowed players to choose the starting configuration.
• In practice: “Reversi” and “Othello” are now interchangeable terms for the same game.

Reversi history

• 1880s — Lewis Waterman & John Mollett: rival claimants to inventing Reversi in England.
• 1893 — Ravensburger: the German publisher starts producing Reversi.
• 1973 — Goro Hasegawa: Othello launches in Japan. Modern starting position standardized.
• 1977 — Othello world championship: first international tournament.
• 1980 — the program Moor wins one game of six against world champion Hiroshi Inoue.
• 1993 — 6×6 solved. Joel Feinstein shows the second player wins with perfect play.
• 1997 — Logistello beats Murakami: world champion loses to AI. Computers surpass top humans.

Common mistakes

• Grabbing X-squares. Tempting because they flip discs, but they give opponent corner access.
• Over-flipping. Flipping many discs feels good but reduces your mobility.
• Ignoring mobility. Material count is misleading mid-game. Mobility matters more.
• Building unstable edges. Edge discs without corner backing can flip via “wedging.”
• Greedy openings. Aggressive early play often leaves position-weakening tradeoffs.

Variants

• Othello (standard 8×8). The modern game.
• Reversi 6×6. Smaller, faster — solved as a second-player win with perfect play.
• Reversi 10×10. Larger board, more complex.
• Cylindrical Reversi. Left and right edges wrap around.
• Anti-Othello. Player with the FEWEST discs at end wins.

FAQ

• Q: Are Reversi and Othello the same game? A: Modern Othello and Reversi use identical rules. Historically Reversi had variations; Othello’s trademark fixed them.
• Q: What’s a “wipeout”? A: Winning with opponent having zero discs remaining. Rare but possible.
• Q: Is Othello a draw with perfect play? A: Very likely: a 2023 computer analysis reported that perfect play on 8×8 ends in a draw. The 6×6 variant is solved as a win for the second player.
• Q: Can I beat strong AI? A: Not the top programs, which play at superhuman level. Our CPU is much more beatable: Easy searches 2 half-moves ahead, Medium 4 and Hard 5, weighing corners, edges and mobility.

For other strategy board games, try Chess, Checkers, Reversi 6×6, or Connect Four.