Flip the lines, hold the corners

Set a river stone on the slate so it traps a line of your opponent's, and watch the line turn over one stone at a time. Black basalt against white quartz, a paper lantern, and a garden going quiet at dusk.

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Genre: Board game
Controls: Touch
Mouse
Keyboard
Devices: Desktop
Tablet
Mobile
Released: 2026

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Reversi

Reversi is played on an eight by eight grid cut into a slab of slate, set flush into raked white gravel. Each stone is a river pebble — matte black basalt on one side of the table, pale quartz on the other — and every one of them can change hands. Place a stone so that it traps a straight run of your opponent's between it and another of yours, and the whole run turns over. Lines go in all eight directions, and a single stone can turn several of them at once.

The trick is that turning the most stones is usually the worst thing you can do. Every stone you flip is a stone that can be flipped straight back, and a fat pile in the middle of the board leaves your opponent squares to play into. The players who win count squares instead: they take the edges, they leave the four squares beside each corner well alone, and they wait until the other side has nowhere good left to go. A corner can never be turned, which is why the whole game bends towards them. With no legal move you simply pass, and when neither side can move the stones are counted and the larger colour takes it.

Play Black or White against Easy, Normal or Sharp, or pass the device back and forth with a friend — in face-to-face mode each player's counter turns to face them. Legal squares show as faint dots you can switch off, the stones that would turn are outlined before you commit, moves are written down in a1 to h8 notation beside the board, and a bar along the bottom shows the count swinging back and forth. Twenty-four puzzles set you a position with one best stone, from quiet openings to endgames you can read to the last square. The Sharp opponent searches several moves deep and solves the last twelve squares exactly, so the finish is never sloppy.

Tips for Reversi

In Reversi, turning the most stones is usually a mistake. Every stone you flip can be flipped straight back, and a big pile in the middle of the board leaves your opponent more squares to play into. Think about squares rather than stones. A corner can never be turned, so corners are the squares the whole game bends towards, and the edges come next. Leave the four squares beside each corner well alone.

The aim is to wait until the other side has nowhere good left to go. Before you place a stone, look at the outline showing which stones will turn, and think about which squares that opens up for your opponent. Start against Easy with the legal-move dots on, then switch them off with L once you can see the moves yourself. The twenty-four puzzles each have one best stone and a note on why, which makes them a good way to learn the ideas. If you have no legal move, you simply pass.

How to play Reversi

Reversi is played on an eight by eight board by two sides, Black and White, who take turns placing one stone at a time. Choose your colour and play against the computer at Easy, Normal or Sharp, or pass the device back and forth with a friend.

A move is only legal if it traps some of your opponent's stones. You trap them by placing your stone so that a straight, unbroken line of your opponent's stones sits between the new stone and another of yours. The line can run across, up and down or diagonally, eight directions in all, and every trapped stone turns over to your colour. One stone can trap several lines at once, and all of them turn. If you have no legal move, you pass and your opponent plays again. The game ends when neither side can move: the stones are counted, and the colour with more on the board wins. A bar along the bottom shows the count swinging as you play.

Reversi helps you while you learn. Legal squares are marked with faint dots, which L switches on or off, and the stones that would turn are outlined before you commit. You can undo and ask for a hint, and every move is written down in a1 to h8 notation beside the board. On a phone or tablet, tap a square to place your stone; on a computer, click it or use the arrow keys and Enter. P pauses and M mutes.

About Reversi

Reversi is a classic strategy game for two that goes back to the nineteenth century. Its rules fit in a few sentences, yet the game rewards years of practice. Stones change hands all the time, so the lead swings back and forth until the very end, and the player with fewer stones in the middle of the game is often the one in the better position.

Kiloo's Reversi sets the board in a quiet garden at dusk: a slab of slate in raked white gravel, black basalt and pale quartz river stones, and a paper lantern. It suits beginners and strong players alike. Newcomers can lean on the legal-move dots, the flip preview, undo and hints, and start against Easy. Experienced players can take on Sharp, which searches several moves deep and solves the last twelve squares exactly. The twenty-four puzzles, each with one best stone and a note on why, are a good way to learn the ideas behind corners and edges, and in face-to-face mode each player's counter turns towards them when two people share a tablet.

Frequently asked questions

Is Reversi free to play?

Yes. Reversi is free to play in your browser on Kiloo. There is nothing to download and no account to create. Play Black or White against the computer, or pass the device back and forth with a friend.

Can I play Reversi on my phone?

Yes. On a phone or tablet you tap a square to place your stone there. On a computer you can click, or use the arrow keys and Enter. L turns the legal-move dots on or off, and in face-to-face mode each counter turns towards its player.

What happens if I have no legal move in Reversi?

If you have no legal move, you simply pass and your opponent plays again. When neither side can move, the stones are counted and the colour with more on the board wins the game.

How strong is the Sharp opponent?

Sharp searches several moves deep and solves the last twelve squares exactly, so its finish is never sloppy. Easy and Normal are gentler, and you can play either colour against any of the three.

What are the rules of Reversi?

In Reversi you place a stone so that it traps a straight line of your opponent's stones between it and another of yours, in any of eight directions, and the trapped stones turn to your colour. With no legal move you pass. When neither side can move, the colour with more stones wins.

Are there puzzles in Reversi?

Yes. Reversi has twenty-four puzzles, from quiet openings to endgames you can read to the last square. Each one sets you a position with a single best stone to find, and a note explains why that move is the right one.