How to play
Reversi is a strategy game for two players on an 8 × 8 board. One player has dark discs and the other has light discs. On your turn you place one disc of your colour so that it traps a straight line of your opponent's discs between the new disc and another disc of yours. Every trapped disc flips to your colour. When neither player can move, the player with more discs wins.
Play the computer on Easy, Medium or Hard, or choose 2 players to share the screen with a friend. Against the computer you can take Dark, which always moves first, or Light and let the computer open. Small dots mark every square where you may place a disc, and you can switch them off with Show legal moves.
Rules
- Start. The game begins with four discs in the centre: light on d4 and e5, dark on d5 and e4. Dark moves first.
- Legal moves. A move must flip at least one opponent disc. Starting from the empty square you choose, look in any of the eight directions: if you see one or more opponent discs followed directly by a disc of your own, all the discs in between are flipped.
- Several lines at once. One move can flip discs in several directions. Every line that is closed by one of your discs flips.
- Passing. If you have no legal move you must pass, and the game tells you so. Your opponent then moves again. You may never pass when you do have a move.
- End of the game. The game ends when neither player can move, which usually happens when the board is full. The player with more discs wins; equal numbers make a draw.
Controls
Mouse and touch
- Click or tap an empty square to place a disc. If the move is not legal, the game explains why and nothing changes.
Keyboard
- Tab moves focus to the board. The ← ↑ → ↓ keys move the cursor, and each square is announced with its name and state, for example “d3, empty, legal move”.
- Enter or Space places a disc on the square under the cursor.
- U takes back a move and H shows a hint.
Buttons
Undo takes back your last move together with the computer's reply; in a two-player game it takes back one move. Hint highlights a good move, and New game starts over. The last disc placed is marked with a small yellow dot.
Tips and strategy
- Corners are gold. A disc in a corner can never be flipped, and it gives you a safe anchor along both edges.
- Avoid the squares next to empty corners. The squares diagonally next to a corner (the X-squares) and the two beside it on the edge (the C-squares) often hand your opponent the corner.
- Mobility beats disc count. Early on, having fewer discs is usually an advantage, because it leaves your opponent with fewer good moves. Try to keep your options open and limit theirs.
- Build stable edges. Discs next to your own corner discs along an edge cannot be flipped, so they count for certain at the end.
- Count in the endgame. With about ten empty squares left, work out the exact results of your options. Making the last move in a region is often worth a lot.
Frequently asked questions
What happens if I have no legal move?
You pass automatically. The message “No moves — pass” appears under the board and your opponent plays again until you can move. If neither player can move, the game is over.
Is a player with more discs always winning during the game?
No. The count only matters at the end. A player who has many discs in the middle of the game often has few safe moves left, so the lead can change very quickly.
How strong is the computer?
Easy plays mostly random moves, with a slight liking for moves that flip many discs. Medium looks four moves ahead and values corners. Hard searches deeper in under a second per move, weighs mobility and stable edges, and solves the last twelve or so empty squares exactly.
Why does Hard sometimes take a moment?
It searches for up to about a second, and the board stays locked until it has moved. The dots next to its name show that it is thinking.
Is my game saved?
Yes. The game in progress is saved in your browser and continues after a reload. Your wins, losses and draws are stored for each difficulty level. If your browser blocks storage, nothing is remembered.
Does it work offline?
Yes. Once the page has loaded, you can play without an internet connection.
More free games
- Checkers – jump and crown kings against the computer.
- Four in a Row – line up four discs first.
- Tic-Tac-Toe – the quick classic for two.
- Nonogram – reveal a picture with number clues.
- Memory – find all the matching pairs.
- Sudoku – fill the grid with logic.
- Minesweeper – clear the field without a blast.
- 2048 – slide and merge tiles.