How to play Reversi
Reversi is a classic board game for two, played here against Ben, the computer. You play the black discs and Ben plays white. You take turns putting a disc on the board, and every disc you trap between two of yours flips over to your color. When neither of you can move, the player with more discs wins.
The board
The board has 64 squares, eight across and eight down. The columns are lettered A to H and the rows numbered 1 to 8, so every square has a name, like D3. The game starts with four discs in the middle: two black and two white, set diagonally. Black (you) moves first.
Making a move
- Put your disc on an empty square so that it traps one or more of Ben's discs in a straight line (across, down or diagonally) between the new disc and another of yours.
- Every trapped disc flips to black. One move can trap discs in several directions at once, and they all flip.
- A move must flip at least one disc. The board marks the squares where you can play; tap one to put your disc there. (You can turn the marks off in Settings.)
- If you can't move, you pass and Ben plays again; the same goes for Ben. When neither of you can move, usually because the board is full, the game is over and the player with more discs wins.
Tips
We measured these by letting Ben play hundreds of games against copies of Ben that each ignored one tip. They're listed with the most valuable first.
- Stay off the squares next to an empty corner. A disc on B2, B1 or A2 (and the same squares by the other corners) can let Ben into that corner. Once a corner is taken, its neighbors are safe again.
- Keep your options open. In the middle of the game, it's better to have plenty of moves to choose from, and to leave Ben with few, than to flip lots of discs. The count only matters at the end.
- Take the corners. A disc in a corner can never be flipped back, and it lets you build lines of safe discs along the edges.
- Edges help a little. Edge discs are hard to flip, unless Ben can trap them along the edge itself.
- Ask for a hint. It shows the move Ben would make in your place, and explains why: a corner, a safe edge, or a move that leaves Ben with few choices.
Questions
How good is Ben?
Choose a level in Settings. On Easy, Ben plays like a beginner: the move that flips the most discs, and a corner whenever one is offered. On Medium, Ben looks three moves ahead and knows the value of corners and edges. On Hard, Ben looks five moves ahead and, in the last ten moves, counts out every way the game can end. In our tests, Medium won every game against Easy, and Hard beat Medium 93 games in 100.
Does it matter who goes first?
Not much. You always play black and move first, and in our tests between equal players, black and white each won about half the games.
Is any money involved?
No. Reversi here is played just for fun: there's no betting, no prizes and no real money, and nothing to buy.
Can I take back a move?
Yes. Undo takes back your last move, and Ben's reply. Your game also saves itself, so you can stop at any time and carry on later.
Where does Reversi come from?
Reversi was born in England in the 1880s. Two Englishmen, Lewis Waterman and John W. Mollett, each claimed to have invented it in 1883, and each called the other a fraud. A version with a fixed starting position became a worldwide hit in the 1970s, and the game has been a family favorite ever since.