The best Othello strategy is not to flip as many discs as you can. Count moves, not discs: try to leave your opponent few moves and yourself plenty, take the corners, and stay off the X-squares and C-squares next to an empty corner, because those are how corners get given away. Discs only count at the very end, so having fewer of them in the middle of the game is often a good sign.
Reversi and Othello play by the same rules, so everything here works for both. We didn't want to repeat tips just because every guide repeats them, so we tested each one with thousands of computer games in Poozee's Reversi, and we checked every worked example with an exact endgame search. Here's what held up.
How we tested
We ran two kinds of test.
Simple players. Each follows one rule of thumb and otherwise plays at random: "flip the most discs", "take a corner when you can", and so on. Each played 2,000 games against a player that picks any legal move at random.
The full computer player. Poozee's engine scores a position by its mobility, corners, X- and C-squares, frontier discs and stable discs. For each habit, we switched it off in one copy and had that copy play 1,000 games against the full version, with both looking two moves ahead (its own move and the reply).
In every test, the first 6 moves of each game were random, and each random opening was played twice with the colors swapped, so neither side got the better start. A draw counts as half a win, so 50% means the habit made no difference.
1. Count moves, not discs
The most common beginner habit is to grab as many discs as possible. It's better than nothing, but not by much:
| Simple player's rule | Score against a random player |
|---|---|
| Flip as many discs as possible | 62.2% |
| Flip as few discs as possible | 39.0% |
| Leave the opponent as few moves as possible | 69.1% |
The greedy player's discs are fragile. Every disc you flip is a disc your opponent might flip back, and a wall of your discs gives your opponent lots of places to play. When the move-counting player played the greedy one directly, it scored 62.1%, and it usually did that while behind: after 20 moves, the greedy player had more discs in 1,788 of 1,989 games, and went on to win only 676 of them.
Flipping as few discs as possible isn't the answer either: on its own it did worse than random. Fewer discs is only good when it means fewer moves for your opponent.
Having more discs early doesn't predict the winner
We also had two copies of the full computer player play 1,000 games against each other, and checked who was ahead in discs as the game went on (the 22 drawn games are left out):
| After this many moves | Player with more discs went on to win |
|---|---|
| 20 | 44.6% |
| 40 | 51.2% |
| 50 | 64.1% |
After 20 moves, the player with more discs won less than half of the time. Even after 40 moves, two thirds of the way through a full game, being ahead was a coin flip. Don't panic when your opponent has twice as many discs in the middle game.
Worked example: the quiet move
White has five moves. The greedy one is g4, which flips six discs. It loses: with best play from both sides, Black wins by 14. The quiet h4 flips a single disc (g5) and wins by 14 with best play. We checked every move with an exact search to the end of the game, so these margins are exact, not estimates.
Pro tip: Before you play, count your opponent's replies. The move that leaves them the fewest safe moves is usually better than the one that flips the most.
2. Take the corners
A disc in a corner can never be flipped, because nothing can get on both sides of it. Corners also anchor the edges next to them. Of our simple players, "take a corner whenever you can" scored 76.0% against a random player.
In the 1,000 games between two copies of the full computer player, the winner ended the game with more corners than the loser in 752 of the 978 decided games, and with fewer corners in only 60.
3. Stay off the X-squares and C-squares
The corners are worth so much that the squares next to them are dangerous. An X-square is diagonally inside a corner: b2, g2, b7 and g7. A C-square is on the edge right next to a corner, like b1 and a2. While the corner is empty, a disc on one of them often gives your opponent a way into the corner.
| Simple player's rule | Score against a random player |
|---|---|
| Avoid X-squares next to an empty corner | 58.4% |
| Avoid C-squares next to an empty corner | 73.3% |
| Avoid both | 89.6% |
| Avoid both, and take corners | 92.8% |
Avoiding both kinds of square did more than any other single rule we tried. For the full computer player it was the same story: switching off the X-square penalty hurt it more than switching off anything else (see the table in section 4).
Black can take the a1 corner and win by 18 with best play. Four other moves also win. The one move that loses is g7, the X-square next to the empty h8 corner: White's best answer is to take h8, and Black then loses by 4.
These are rules of thumb, not laws. Late in the game, an X- or C-square is sometimes the best move, when the corner can't be taken or the square wins something bigger. Check whether your opponent can actually reach the corner before you rule a move out.
4. What mattered most to the computer
Here's how the full computer player did with one part of its judgment switched off, against the full version:
| Part switched off | Score of the version without it |
|---|---|
| X-square penalty | 26.9% |
| Mobility (having more moves than the opponent) | 39.2% |
| Corners | 40.9% |
| Stable discs | 42.0% |
| Frontier discs | 44.0% |
| C-square penalty | 44.6% |
| All of it, counting discs instead | 10.9% |
Every part helped, and the version that only counted discs won barely one game in ten. Frontier discs are your discs next to an empty square: they give your opponent something to flip and somewhere to play. Keeping your discs in the middle, walled in by other discs, keeps your frontier small. Stable discs are ones that can never be flipped, usually because they're anchored in a corner.
5. In the endgame, make your opponent pass
A player with no legal move has to pass, and then you move again. Near the end of the game, a free extra move is often decisive.
Black has nine legal moves, and the exact search says eight of them lose. The winner is b8, which flips just one disc (b7). After it, White has no legal move and has to pass, so Black plays again, and wins by 6 with best play.
When you count the empty squares near the end, look for moves that leave your opponent stuck. The same idea works in reverse: avoid moves that give your opponent a free pass.
Practice against the computer
Poozee's Reversi has four levels. Easy leans toward whatever move flips the most discs, which makes it a good first opponent for trying out corners and quiet moves. Medium looks two moves ahead and knows corners are valuable. Hard looks four moves ahead with the full evaluation from this test and plays the last 10 moves perfectly. Expert thinks for up to a second a move. You can play Black or White, and Hint shows the move Expert would play for you.
Is Othello solved?
Yes. In a paper first posted on arXiv on October 30, 2023, "Othello is Solved", Hiroki Takizawa announced a computer proof that with perfect play by both players, Othello on the standard 8 by 8 board ends in a draw. No person can play that way, so the tips above are still how games are won and lost.
Keep playing
- Play Reversi against the computer or a friend
- How to win at checkers, another board game we tested by computer self-play
- How to win Connect Four
- Dots and boxes strategy, where forcing your opponent's moves also decides the endgame
Frequently asked questions
What is the best strategy in Othello?
Take corners when you can, stay off the squares next to an empty corner, and try to leave your opponent as few moves as possible. In our tests, a player that only avoided the squares next to empty corners, and otherwise moved at random, scored 89.6% against a player moving at random.
Is it good to have more discs in Othello?
Not until the very end. When two copies of our computer player played each other, the one with more discs after 20 moves went on to win only 44.6% of the games that had a winner. Discs only count once the board is full, so early on it pays to have fewer discs and more moves.
What are X-squares and C-squares in Othello?
An X-square is the square diagonally inside a corner (b2, g2, b7 and g7). A C-square is an edge square right next to a corner (like b1 or a2). While the corner is empty, a disc on either one often lets your opponent take the corner.
Is Othello a solved game?
Yes. In a paper posted in October 2023, Hiroki Takizawa announced a computer proof that with perfect play by both players, Othello on the standard 8 by 8 board ends in a draw.