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Reversi

Outflank discs to flip them to your color — against the computer or a friend in local 2-player mode. Most discs at the end wins.

Hard

⚫ You: 2⚪ CPU: 2

You are Black. Click a dotted square to play.

How to Play

Choose a mode at the top: Vs Computer (you are Black) or 2 Players (Player 1 is Black, Player 2 is White, sharing this device). Black moves first; legal squares for the player to move show a small dot.

Place a disc so it traps one or more opponent discs in a line between your new disc and an existing disc of your color.

All trapped discs flip to your color — flips can chain in up to 8 directions at once.

If the player to move has no legal move they pass automatically; the other side passes too when it is stuck, in both modes.

When neither side can move, the player with more discs on the board wins.

Controls

Click dotted squarePlace a disc for the player whose turn it is and flip

Vs Computer / 2 PlayersSwitch mode and start a fresh game

New GameReset the board

Tips

•Corners can never be flipped — fight for them above everything else.
•Having fewer discs mid-game is fine; mobility (many legal moves) matters more.
•Avoid giving your opponent the squares next to corners early on.

About Reversi

Reversi — sold worldwide under the name Othello — is the board game famous for the slogan 'a minute to learn, a lifetime to master'. It is played on an 8×8 board, and this version has you playing Black against the computer's White. A move is only legal if your new disc traps at least one line of white discs between itself and a disc you already own; everything trapped flips to black. A single well-chosen move can flip discs in up to eight directions at once and redraw the whole look of the game.

The trap for beginners is greed. Flipping the most discs early feels powerful, but it usually hands your opponent more legal moves and opens the routes to the corners — and a corner disc can never be flipped, anchoring every line that touches it for the rest of the game. Strong Reversi is often about having fewer discs in the mid-game, keeping your opponent's options narrow and yours wide, then flipping in bulk once the board starts to lock down.

The computer here plays with exactly those ideas in mind: it weighs squares positionally (corners gold, squares beside corners dangerous), counts flips, and checks how many replies a move leaves you. If neither side can move the game ends early — passing is automatic when you are stuck — and the player holding more discs wins. Legal moves are marked with dots, so the learning curve is gentle even while the strategy runs deep.

How to Play Reversi

You are Black and you move first. The four centre discs are already placed, and your legal squares are marked with small dots.

Click a dotted square to place a disc. The move is legal only if it outflanks at least one straight line — horizontal, vertical or diagonal — of white discs ending at one of your existing black discs.

Every trapped white disc in every qualifying direction flips to black automatically.

The computer replies, flipping your discs the same way. Watch the running disc counts, but remember the mid-game count is not the score that matters.

If you have no legal move, you pass automatically and the computer moves again — and the computer passes in the same situation.

When neither side can move, the game ends and the player with more discs on the board wins.

Controls

Click a dotted squarePlace a black disc and flip all outflanked white discs

New Game buttonReset the board to the starting position

Tap (touch)Moves work with taps on mobile

Tips & Tricks

💡Corners are forever. A disc in a corner can never be flipped, and it stabilises the discs along both edges — fight for corners above every other consideration.
💡Beware the squares next to corners. Playing into the diagonal neighbour of an empty corner usually hands your opponent that corner on the very next move; the edge neighbours are nearly as risky early on.
💡Count your options, not your discs. A move that leaves you with many legal replies and your opponent with few is usually stronger than a move that flips one or two extra discs.
💡Keep your discs compact in the middle game. A sprawling frontier of discs gives the computer more lines to attack; a tight cluster limits what it can flip.

Reversi — Frequently Asked Questions

What happens if I have no legal move?+

You pass, automatically — the game tells you and hands the turn back to the computer. The same applies to the computer when it is stuck. If both sides are stuck in a row, the game ends and discs are counted.

Is Reversi the same as Othello?+

Essentially yes. Othello is the trademarked commercial version of the older public-domain game Reversi, with the same flipping rules and the same fixed four-disc centre start used here.

How strong is the computer opponent?+

It evaluates moves with positional weights (corners and stable edges score highly), the number of discs flipped, and how many legal replies the move leaves you, with a small random element so games vary. It punishes greedy corner-adjacent play and makes a solid sparring partner while you learn real strategy.

Can the game end in a draw?+

Yes — if the board fills or locks up with both sides holding exactly 32 discs, the game is tied. It is rare, but it happens most often in very defensive games.