Reversi Strategy: Corners, Mobility and the Danger Squares
How to win at Reversi: stay off the squares next to empty corners, keep your options open, take corners, value edges, and why fewer discs early can help.
Sunroom Games · Updated
Reversi takes a minute to learn: trap your opponent's discs between two of yours and they flip to your color. Playing it well is another matter, because the move that flips the most discs is very often the wrong one. To find out which habits matter most, we let Ben, our computer player, play hundreds of games against copies of Ben that each ignored one piece of advice.
If you'd like the rules first, see how to play Reversi.
What our test games showed
We played 200 games for each comparison, with the two sides taking turns to play black. Both sides looked three moves ahead, like Ben on Medium. Against a player who ignored one habit, the player who kept it won:
| Habit | Games won out of 100 |
|---|---|
| Staying off the squares next to an empty corner | 83 |
| Keeping plenty of moves to choose from | 81 |
| Taking the corners | 70 |
| Valuing the edges | 57 |
One more surprise: a player who preferred having fewer discs during the game won 54 games to 43 against one who didn't care (the rest were drawn). The count only matters at the very end.
1. Stay off the squares next to an empty corner
Each corner has three neighbors: the diagonal square (like B2) and the two edge squares beside it (like A2 and B1). Put a disc there while the corner is still empty, and you can hand the corner to your opponent, who only needs to trap your disc against one of theirs.
This was the most valuable habit of all in our tests. The careful player ended up with more than three of the four corners in an average game, and the player who ignored the danger squares with fewer than one. Once a corner is taken, its neighbors are safe again.
2. Keep your options open
In the middle of the game, the number of moves you can choose from matters more than the number of discs you have. A player with plenty of choices can wait for a good square, while a player with only one or two may be forced onto a danger square. Before you play, glance at what the move leaves for Ben: fewer choices for Ben is usually good for you.
That's also why grabbing discs early can backfire. Every disc you flip is one more of yours that Ben can trap, and one more line Ben can play through. In our tests, the player who preferred fewer discs during the game came out ahead.
3. Take the corners
A disc in a corner can never be flipped back, because nothing can trap it. From a corner, you can build lines of safe discs along both edges.
Corners came third in our tests, which may seem low. One likely reason: a player who already stays off the danger squares rarely gives a corner away in the first place, so the other player gets fewer chances to take one.
4. Edges help a little
Edge discs are harder to flip than discs in the middle, because they can only be trapped along the edge itself. Valuing them helped, but less than the habits above: 57 games in 100. Watch out for gaps along an edge, where a disc of Ben's can slip in and trap a whole row.
5. Count at the end
In the last few moves, the score is what counts again. When the board is nearly full, look for the move that leaves you with the most discs once both of you have played out. Our Hard level counts every way the game can end in its last ten moves; the hint uses it too, so it's a good way to learn how an ending works.
6. Ask for a hint
Our Hint button shows the move Ben would make in your place and explains why: a corner, a safe edge, a move that leaves Ben with few choices, or a move that forces Ben to pass.
How often should you win?
Ben has three levels. On Easy, Ben plays like a beginner: the move that flips the most discs, and a corner whenever one is offered. That style beat a player making random moves 76 games in 100 in our tests. Medium, which looks three moves ahead and knows the danger squares, beat Easy in every one of our test games, and Hard beat Medium 93 games in 100. Who moves first makes little difference: between equal players, black and white each won about half the games.
If the habits above are new to you, start on Easy and move up when you're winning most games. For more two-player strategy, see our guides to Checkers and Backgammon.