Game The short answer
In all 3 positions the move that flips the most discs was not the best move, with a gap of 6 to 20 discs. Flip count does not tell you which move is best.
What we are testing
When you first learn Othello, it is tempting to play the move that flips the most discs. More discs wins, so more must be better — that is the intuition. But only the final count decides the game; how many you hold along the way is irrelevant. Let's see whether that intuition really backfires, by solving a real position to the very end.
How we tested it
Every number here is output from our own solver (negamax with alpha-beta). We take an endgame position with few empty squares, play each legal move in turn, and solve what follows to the very end of the game. There is no evaluation function and no approximation, so the margins are exact rather than estimated. One position cannot show how typical something is, so each article solves three.
Position by position
Black has seven legal moves. The one that flips the most is a4, with four discs. Solving every move to the end of the game gives this (margin is Black's final disc differential, best play by both sides):
| Move | Discs flipped | Final margin | Note |
|---|---|---|---|
| g8 | 1 | +4 | only win |
| a4 | 4 | −6 | most flipped |
| h3 | 2 | −6 | — |
| h2 | 3 | −6 | — |
| b7 | 2 | −14 | — |
| b5 | 2 | −14 | — |
| h4 | 3 | −16 | — |
Where the difference comes from
In this position, discs flipped and final result run almost exactly opposite. The move that flips the most, a4 (four discs), loses at −6. Meanwhile the only winning move is g8, which flips just one disc (f7) and finishes +4.
Every two- and three-disc move (h3, h2, b5, …) loses as well. The single road to a win was the most unassuming one-disc move. Between the player who grabs the most and the player who takes the fewest, the final margin differs by 10 discs.
Exceptions
The mirror image of the rule - flip as few as you can - does not survive this table either. The two-disc moves b7 and b5 finish at −14, and the three-disc h4 at −16: all below the four-disc a4 at −6. High or low, the flip count is not the signal.
Why the one-disc g8 is the only win, the solver does not say; all it returns is the final margin. What the numbers support is the narrow claim - flip count does not order the moves - and the reason behind any particular move has to be read out position by position.
Playing the best move
Watch the only winning move, g8, being played: the disc goes down first, then the captured discs turn over one at a time. The gold frame marks the square played; the gold rings mark the discs that flipped.
As stated in our editorial policy, the numbers are the real computed results, printed as-is.
Does it hold in other positions?
To see whether the same thing happens elsewhere, we solved more positions where a maximum-flip move was available.
| Position | Best move | Move tested | Gap (discs) |
|---|---|---|---|
| Case 1 | g8 +4 | a4 −6 | 10 |
| Case 2 | a2 +8 | a8 +2 | 6 |
| Case 3 | e7 +18 | b5 −2 | 20 |
Across the 3 positions the gap ran from 6 to 20 discs — that is how differently the same mistake can be punished, depending on where it happens.
Case 2 — 10 empty squares
Best was a2 (+8). the maximum-flip move — a8 — gives +2, a gap of 6 discs.
| Move | Flips | Final margin | Diff vs best |
|---|---|---|---|
| a2 | 4 | +8 | best |
| a8 | 7 | +2 | -6 |
| h6 | 1 | +2 | -6 |
| a5 | 5 | ±0 | -8 |
| g3 | 1 | ±0 | -8 |
| a7 | 4 | −12 | -20 |
| g8 | 2 | −14 | -22 |
Case 3 — 10 empty squares
Best was e7 (+18). the maximum-flip move — b5 — gives −2, a gap of 20 discs.
| Move | Flips | Final margin | Diff vs best |
|---|---|---|---|
| e7 | 1 | +18 | best |
| e1 | 3 | +16 | -2 |
| c8 | 6 | +10 | -8 |
| a8 | 3 | +8 | -10 |
| a6 | 2 | +8 | -10 |
| h6 | 5 | +6 | -12 |
| b5 | 7 | −2 | -20 |
The same question over 400 positions
The positions above are solved one move at a time. The same question was also counted over 400 random positions (10 empty squares, 2617 moves solved in total).
The maximum-flip move was best in 76 (19%), costing 13.99 discs on average if played every time. The minimum-flip move — the opposite rule — was best in only 90 (22.5%), costing 11.13 discs. Neither direction of the flip count finds the best move.
What this does and does not show
- It shows: for these 3 positions, an exact solve of every legal move to the end of the game. Not an approximation.
- It does not show: anything about every position — 3 is a very small sample. For a wider count see the 400-position study.
- The assumption: the margins assume best play from both sides to the end.
- Reproducing it: the positions and results are in
assets/othello-analysis.json, regenerated bytools/generate-othello-analysis.mjs.
What to remember at the board
- In all 3 positions the maximum-flip move was not best
- Across 3 positions the gap ran from 6 to 20 discs — how much it costs depends on the position
- Over 400 positions it was best 19% of the time — and the minimum-flip move only 22.5%
- Look at what the opponent can do next, not at how many discs turned
Try it yourself
You can set these positions up and play them out. The evaluation bar moves after every move, so the difference between a good move and a poor one shows up as you play.
Check the same position yourself
Try the "take fewer" idea with the evaluation bar watching. Free, no account.
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