Itte Dojo
一手道場

Reversi strategyGuides with solved examples

The shapes that most often cost discs in reversi (Othello), and why. Most guides have a board where you can try the moves. The numbers are final disc margins from an engine that reads the position to the end (exact search).

  1. 01Corners, X-squares and C-squaresA disc on a corner can never be flipped. The squares next to a corner, the X-squares and C-squares, are the usual way to hand that corner to your opponent.2 examples
  2. 02Mobility: leave fewer movesIn reversi, a player with no legal move must pass. The fewer moves your opponent has, the more often they are forced into bad ones.1 example
  3. 03Openness and quiet movesTwo similar moves can give your opponent very different options, depending on which discs they flip. Openness puts a number on it.1 example
  4. 04ParityIn the endgame, the empty squares split into separate regions. Whoever plays last in a region leaves the opponent no square there to answer from.1 example
  5. 05How to read the endgameWith about 10–16 empties left, the number of moves is small enough to read to the end. In the endgame, reading decides more than principles.
  6. 06Reversi openingsOpenings are standard move orders for the first moves of the game. Step through each named line on the board.
  7. 07How often is parity right?Solving 3,600 positions exactly: in the 1,740 with moves in both odd and even regions, the best move was in an odd region 72% of the time. Picking any odd-region move gained almost nothing.

How these guides are made

The text summarises widely known reversi principles. The example positions are picked automatically from games, and every move is solved to the end to check the disc margin. Principles have exceptions, so each example shows in numbers what following the principle is worth in that position.

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