Reversi Guide: Outflanking, Corners, and Mobility

Reversi is the classic two-disc game, played here by two people on one device. The game starts from the standard four center discs — black on d5 and e4, white on d4 and e5 — and black places first. Every move must outflank at least one opponent disc in a straight line, and every outflanked disc flips to your color. A player with no legal move passes; the game ends when the board is full or neither player can move, and the player with the most discs wins.

How to play

Place your disc on any square that outflanks one or more of your opponent’s discs in a straight line — horizontal, vertical, or diagonal. Every outflanked disc between your new disc and a disc of your color flips to your side; a move can flip in several directions at once.

If a player has no legal move, the game passes automatically and the other player continues — there is no choice involved. The board ends when it is full or when both players have nothing to play, and the count is settled: most discs wins.

Controls

• Mouse or touch: tap or click any highlighted (legal) square.
• Keyboard: the arrow keys move only between squares that are legal, so a keyboard turn is never refused — press Enter to place.
• Legal-move hints: playable squares are marked by default; the toolbar button hides the markers if both players prefer reading the board themselves.
• Pass the device: the handoff screen covers the board after each move; Continue passes play on.

Flips animate once for motion-tolerant players and never for reduced-motion players.

The habits that decide games

Corners are the most valuable squares

A corner disc is adjacent to only three lines, so once it is yours it is far harder to flip than any edge or center disc. Most of the midgame is about giving and refusing corners: a move that lets your opponent take a corner on the next turn is usually a real cost.

Count your options, not just your discs

Mobility — how many legal moves a position gives you — matters more than the disc count on the board. A move that leaves your opponent with many good options is a gift, even if it flips several discs; a move that narrows the board to a handful of lines is a threat, even if it flips only one.

Sacrifice with a purpose

Deliberately giving up discs is a standard tool: you might accept a small loss to steer the board toward a line where you will flip many at once, or to hand the move to a player who is about to take a bad corner. The sacrifice is only good if it buys something specific — a corner, an endgame, or the move.

What stays on this device

The most recent result stays on this device and appears in My Arcade as the single record for this game — nothing is uploaded or tied to an account. Clearing site data or using the Privacy page’s Clear game data control removes it.