Reversi Strategy: How to Win More Games

Most people play their first games of Reversi the same way: on every turn they look for the move that flips the most discs. It feels right, and it loses. The count in the middle of the game changes so fast that it means almost nothing. What matters is which discs you own and how many good moves you will have later. This guide covers the handful of ideas that make the biggest difference. If you are new to the game, start with the rules.

1. Corners Are Worth More Than Anything

A disc in a corner can never be flipped. There is no square beyond it, so nothing can ever trap it. Better still, a corner disc makes the discs next to it along the edges safe as well, and that safety spreads. Players who hold two or three corners usually win, even when they are behind in the count.

So when a corner is on offer, take it unless you can see a very good reason not to. And when you are choosing between other moves, ask: does this move let my opponent into a corner?

2. Stay Off the Squares Next to an Empty Corner

The squares touching an empty corner are dangerous, because a disc of yours there is exactly what your opponent needs to trap something and land in the corner.

• The four squares diagonally next to the corners (B2, G2, B7 and G7) are the worst. Players call them X-squares. A disc on B2 almost invites your opponent to take A1 along the long diagonal.
• The edge squares right beside a corner (such as B1 and A2 next to A1) are called C-squares. They are risky too, though less so.

Once a corner is taken, the squares beside it lose their danger. If the corner is yours, they become good squares to build out from.

3. Flip Fewer Discs Early

This is the idea that surprises people most. In the opening and middle of the game, a move that flips just one or two discs is usually better than one that flips eight. Here is why: every disc of yours on the board is a disc your opponent can use to trap something. The more of your discs there are, especially out towards the edges, the more moves your opponent has. The fewer you have, the fewer good moves they have.

Strong players aim for quiet moves: moves that flip a disc or two in the middle, ideally discs that are surrounded on all sides so they don't open new squares for the opponent.

4. Count Your Choices, Not Your Discs

Your number of possible moves is called mobility, and it is the best guide to who is winning in the middle of a game. If you have ten good moves and your opponent has two, you are in charge: soon they will have to play somewhere they don't want to, such as an X-square, and you will get a corner.

Before you move, look at what you leave behind. Our game helps: the dots show all your moves, and after you play you can see how many squares your opponent has. A move that leaves your opponent with only one or two choices is often the strongest on the board. The best of all leaves them with none, so they must pass and you move again.

5. Edges: Good, but Not Automatically

Edge discs can only be flipped along the edge, so they are harder to attack than discs in the middle. But an edge disc that your opponent can trap from both ends is a weakness, and a lone disc in the middle of an empty edge can give your opponent a way in. A good rule of thumb: take an edge square when it can't be trapped right away and doesn't sit next to an empty corner.

6. Avoid Walls

A long solid line of your discs on the outside of the group, facing empty squares, is called a wall. Walls look strong but give your opponent lots of moves along their outside. Try instead to keep your discs on the inside, surrounded by other discs, with your opponent's discs on the outside.

7. The Ending: Now the Count Matters

With a dozen or so empty squares left, things change. Now every disc counts, and careful counting wins games.

• Look for corners and edges that are still open, and work out who will get them.
• Think about who plays last. If an area of the board has an odd number of empty squares, it is usually good to be the one who plays into it first, so you also get the last move there. This idea is called parity.
• Watch for passes. A move that leaves your opponent stuck gives you two moves in a row, and in the ending that can be worth a lot.
• Count both ways. Before each move, check how many discs it flips now and how many your opponent can flip back.

8. A Few Common Mistakes

Practising With the Computer

Our computer player is a good teacher. On Easy it mostly grabs as many discs as it can, which makes it a fine opponent to practise corners against. On Normal it looks a few moves ahead and values corners and edges. On Hard it looks much further ahead and counts the ending exactly, so a win there is a real achievement. Tap Why? beside its moves to see its reasoning, and use Hint when you are stuck: the hint always gives a reason, such as "It takes a corner, and corners can never be flipped." With Undo on, you can take back a move and try another plan.

The same patient, look-ahead thinking pays off in Checkers as well. And for the rule differences you may meet at other tables, see the variations page.