Game The short answer
We solved 2 endgames and compared the best move with the second-best. The difference ran from 4 to 28 discs: how much a single choice is worth changes completely from one position to the next.
What we are testing
By the endgame there are only a handful of moves left. How much does it matter that you pick the best one? Here we measure the distance between the best move and the second best, in an endgame with 8 empty squares where every legal move can be solved to the end. A small gap would mean the choice barely matters; a large one means that single move decides the game.
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 a second was solved here, and the position from the two-corners study gives a third for comparison.
Position by position
Black has 6 legal moves. Solving all of them to the end of the game gives this (margin is Black's final disc differential, best play by both sides):
| Move | Flips | Final margin | Note |
|---|---|---|---|
| a1 | 1 | +14 | Best |
| h4 | 6 | −14 | Second best |
| h8 | 1 | −18 | Corner |
| g1 | 1 | −22 | C-square |
| d8 | 7 | −24 | — |
| g7 | 9 | −28 | X-square |
Where the difference comes from
The best move, a1, finishes +14 — a win. The second best, h4, finishes −14 — a loss. One place apart in the ranking, and the result of the game changes hands. The gap is 28 discs — more than four tenths of the 64 discs that fill the board at the end.
The flip counts point the other way, as usual. a1 turns a single disc, while h4 turns 6 and the worst move, g7, turns 9. It is the same thing the maximum-flip study found, showing up again here.
Exceptions
In this position the second-best move loses on the spot. That is not the rule. In another endgame with the same 8 empty squares, best and second best were 4 discs apart (the table below): either move still wins, and only the size of the win changes.
In the position used for the two-corners study, the same gap was 8 discs. 4, 8, 28: that is how differently one endgame move can weigh. Whether a position is worth reading out carefully is the first thing to judge.
Playing the best move
Watch the best move, a1, 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.
What one move is worth changes
The gap is not always that large. Here is another endgame with the same number of empty squares, solved the same way.
| Position | Best move | Move tested | Gap (discs) |
|---|---|---|---|
| Case 1 | a1 +14 | h4 −14 | 28 |
| Case 2 | c1 +8 | a2 +4 | 4 |
Across the 2 positions the gap ran from 4 to 28 discs — that is how differently the same mistake can be punished, depending on where it happens.
Case 2 — 8 empty squares
Best was c1 (+8). the second-best move — a2 — gives +4, a gap of 4 discs.
| Move | Flips | Final margin | Diff vs best |
|---|---|---|---|
| c1 | 1 | +8 | best |
| a2 | 1 | +4 | -4 |
| g2 | 1 | ±0 | -8 |
| h2 | 3 | ±0 | -8 |
| f1 | 1 | ±0 | -8 |
| b1 | 1 | −2 | -10 |
What this does and does not show
- It shows: for these 2 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 — 2 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
- The gap between best and second-best ran from 4 to 28 discs
- Sometimes the choice barely matters; sometimes it turns a win into a loss
- Do not treat endgame moves as interchangeable — with few empty squares you can read it out
- Where the gap is small, spend the reading time somewhere else
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
Set up the endgame and see how one choice changes the result. Free, no account.
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