Mobility: leave fewer moves

In reversi, a player with no legal move must pass. The fewer moves your opponent has, the more often they are forced into bad ones.

What happens when moves run out

When your opponent has few moves, sometimes only X-squares or corner-giving moves are left. In the middlegame, aim for many moves for yourself and few for your opponent. This is mobility.

Flipping many discs is often bad

With many of your discs on the board in the opening and middlegame, your opponent has more discs to outflank and more moves. With fewer, inner discs, they have fewer moves. Only the final count decides the game, so count discs in the endgame, not before.

Try it on the boardBlack to move · 14 empty squares

Black to move. c1 ends -6 (a loss by 6); the best move h5 ends +6 (a win by 6).

c1 is in an even region (2 empties); h5 is in an odd one (1).
Opponent's moves: 8 after this move, 6 after h5.
Openness: 2 for this move (flips 4), 0 for h5 (flips 2).

Best line: h5 e1 g8 g1 h2 e7 f8 b8

Press a square with a dot to see the result of that move.

Walls and tempo moves

A line of your discs along the outside is a wall. Walls leave you few moves and give your opponent many.

A move that creates no new moves for your opponent is a tempo move. Keep tempo moves for when you need them, and you are less likely to run out of good moves first.

Checking in a game

For each candidate, count your opponent's moves after it.
If they are close, choose the move that flips fewer discs.
Avoid flipping outer discs into a wall unless nothing else is left.

The dojo shows this count after a mistake: "AI's legal moves: n after your move, m after the best move".

Endgame puzzles on this theme

No. 1● Black · 10 empty
No. 2○ White · 11 empty
No. 3● Black · 12 empty
No. 4● Black · 12 empty
No. 6○ White · 13 empty
No. 8● Black · 14 empty
No. 9● Black · 14 empty
No. 10○ White · 15 empty
No. 12○ White · 11 empty
No. 14○ White · 13 empty
No. 16● Black · 10 empty
No. 17○ White · 11 empty
No. 18● Black · 12 empty
No. 19○ White · 13 empty
No. 21● Black · 10 empty
No. 22○ White · 11 empty
No. 23● Black · 12 empty
No. 25● Black · 14 empty
No. 26● Black · 10 empty
No. 27○ White · 11 empty
No. 28● Black · 12 empty
No. 29○ White · 13 empty
No. 31● Black · 10 empty
No. 38● Black · 12 empty
No. 42○ White · 11 empty
No. 43● Black · 12 empty
No. 44○ White · 13 empty
No. 45● Black · 14 empty
No. 48● Black · 12 empty
No. 50● Black · 14 empty
No. 51● Black · 10 empty
No. 53● Black · 12 empty
No. 54○ White · 13 empty
No. 56● Black · 10 empty
No. 57○ White · 11 empty
No. 62○ White · 11 empty
No. 63● Black · 12 empty
No. 64○ White · 13 empty

Play the dojo and get every move graded →