Reversi Online

Reversi is a strategy game for two players, played with discs that are black on one face and white on the other. Every move traps a line of your opponent's discs and turns them over to your colour, so the board can change hands in a single move. The rules take a minute to learn; seeing a few moves ahead takes a good deal longer.

Reversi rules

papergames.io plays Reversi under the standard tournament rules.

• The board has 64 squares, 8 by 8. The game starts with four discs in the centre, two black and two white, each pair on a diagonal.
• Black moves first, then the players take turns.
• On your turn you place one disc of your colour on an empty square. The placement must outflank at least one line of your opponent's discs: an unbroken straight line, horizontal, vertical or diagonal, between the new disc and another disc of yours.
• Every outflanked disc flips to your colour. When the new disc outflanks lines in several directions at once, all of them flip; you never choose which.
• Flipped discs do not set off further flips. Only lines that start at the disc you just placed count.
• When you have no legal move, your turn passes automatically and your opponent plays again. You can never pass while you have a legal move.
• The game ends when neither player can move, usually because the board is full. The player with more discs wins.

The Final score

When the game ends each player counts their discs, and any empty squares left on the board are added to the winner's count. The Final score therefore always adds up to 64, and a draw is 32-32. If one player loses every disc before the board is full, the game stops there and the score is 64-0, however few discs are on the board.

Playing Reversi online at papergames.io

• Hint dots mark every square where you can legally place a disc, so you never have to hunt for a move.
• Create a private room and share the link with a friend.
• Play against a bot at the difficulty that suits you, at any hour.
• Join the daily tournaments and face players from around the world.
• Follow your rating and results on the global leaderboards.

Reversi strategy

New players try to flip as many discs as they can on every move. Strong players often do the opposite. What decides a game of Reversi is not how many discs you hold in the middle of it, but which squares you hold and how many good moves you have left.

Corners

A disc on a corner can never be outflanked, so it never flips. A corner also lets you build lines of safe discs along both of its edges. Corners are not everything, but giving one away for nothing usually costs the game.

The squares next to an empty corner

Three squares touch each corner: the one diagonally next to it, often called the X-square, and the two edge squares beside it, the C-squares. While the corner is empty, a disc of yours on one of them can open a line that lets your opponent take the corner. Stay off them unless you have checked that your opponent cannot use the opening.

Mobility

Mobility is the number of legal moves you have. Keep your own options open and narrow your opponent's: a player left with nothing but bad moves must still play one of them, and that is how most corners are given away.

Frontier discs

A frontier disc is one that touches an empty square. Every frontier disc you own is something your opponent may be able to outflank, which gives them moves. Prefer quiet moves that flip few discs and keep your discs on the inside, over moves that spread a wall of your colour across the board.

Stable discs

A stable disc can never be flipped again for the rest of the game. Corners are always stable, and so is an unbroken row of your discs running along an edge from a corner you own. Stable discs are the only ones you can be sure of at the end, which is why a player with fewer discs but more stable ones is often winning.

Parity

Late in the game the empty squares break up into separate regions. Whoever fills the last square of a region gets a move there that cannot be answered. With no pass, White makes the last move of the game, because the board starts with 60 empty squares; every pass hands that last move to the other player. In the endgame, try to play into regions with an odd number of empty squares and leave the even ones to your opponent.

History of Reversi

Reversi dates from Victorian England, where in the 1880s two men, Lewis Waterman and John W. Mollett, each claimed to have invented it. In early versions the players placed the first four discs themselves. The modern rules fix the starting position, with the four centre discs on the diagonals, and that is how Reversi is played in tournaments today.

Similar games

If you enjoy the positional battle of Reversi, try Gomoku, another game of placing pieces on a grid, where the goal is five in a row. Checkers and Chess share its 8x8 board and its long-range planning, and Connect 4 is a quicker game of placement.

Community and tournaments

Reversi has a long competitive tradition, with national federations and a world championship every year. On papergames.io you can join the daily tournaments, climb the leaderboards and meet opponents of every level, from players learning what outflanking means to those who count the endgame down to the last disc.