Reversi

Two colors of bubble, one board, and a simple rule: trap a line of your opponent's bubbles and they all turn your color.

How To Play Reversi

Taking a turn

Amber goes first. Tap an empty square to drop a bubble there. The move is only allowed if it traps at least one line of your opponent's bubbles between the one you just played and another of yours, with no gaps in between.

Play the bubble on the left and all three in the middle turn amber.

Lines run in any of the eight directions — across, down, and both diagonals — and one move can trap several lines at once. Everything you trap changes color; the wave you see travelling outward is showing you exactly which bubbles you took and in what order.

When you cannot move

If you have no legal move, your turn is skipped and your opponent plays again. The game tells you when this happens. If neither side can move, the game is over, even with empty squares left on the board.

Winning

When the board fills up, or neither side can move, whoever has more bubbles wins. The running count sits at the top of the screen and climbs as the wave passes through, so you can watch a capture pay off.

Settings

Open the settings sheet to change:

Opponent — play the computer, play a friend on the same screen, or sit back and watch the computer play itself.
Difficulty — easy grabs bubbles and misses traps; medium plays the corners properly; hard works out the last dozen moves exactly. Watching it play itself, each side gets its own setting, so you can put one against another.
You play — take Amber and go first, or Aqua and go second.
Animation — how fast the bubbles flip. Calm, normal or quick.
Where you can play — the faint rings marking your legal moves. Hide them once you would rather work it out yourself.
Resting wobble — the slow drift of the bubbles between turns. Turn it off to save a little battery.

Three things worth knowing

Corners are permanent. A bubble in a corner can never be trapped, because there is nothing behind it. Everything you build out from a corner is safe too.
The squares beside a corner are traps. Playing next to an empty corner usually hands that corner to your opponent. Leave them alone until the corner is settled.
Having more bubbles early is bad. Every bubble you own is a bubble that can be trapped, and a big blob leaves you with fewer places to play. Good players stay small for most of the game and take the board at the end.

Tapping a square that is not a legal move does nothing and makes a small sound. If nothing seems to be happening, it is usually because the computer is still thinking, or a capture is still travelling across the board.

Contact: Feel free to contact us with any bugs, complaints, or requests.

Release Date: February 19, 2026

Last Update Date: September 12, 2026

History

Before it became the software powerhouse behind Windows 1.0's premier gaming experience, Reversi was a Victorian-era parlor dispute wrapped inside a brilliant strategy game.

Known today primarily by its modern commercial name, Othello, this game's tagline—"A minute to learn... a lifetime to master"—perfectly summarizes a history spanning over 150 years.

The Victorian Feud (1880s)

The exact origin of Reversi is shrouded in a remarkably petty 19th-century rivalry. Two English inventors, John W. Mollett and Lewis Waterman, both claimed to have invented the game in the late 1880s, routinely denouncing each other in the press as frauds.

The Setup: The game used an 8x8 grid. Players used double-sided discs (usually red on one side, black on the other).
The Twist: Unlike Chess or Checkers, where pieces are captured and removed, Reversi focused on conversion. By trapping an opponent's pieces between two of your own, you flipped their discs to your color.

The game became an instant craze in London, but as the hype faded into the 20th century, Reversi largely fell into obscurity.

The Rebirth: Enter Othello (1971)

The game was entirely reinvented in Japan during the early 1970s by a salesman named Goro Hasegawa.

Hasegawa had played a variant of the game using milk bottle caps as a child. In 1971, he refined the rules, standardized the colors to black and white, and fixed the initial setup to a specific four-piece cross in the center of the board.

Looking for a theatrical name, Hasegawa's father—a Shakespearean scholar—suggested Othello. The name was a brilliant marketing stroke:

The green board represented the battlefield, while the flipping black and white discs mirrored the dramatic shifts, jealousy, and conflicting natures of Shakespeare's Moor of Venice and Desdemona.

Hasegawa registered the trademark, and the game exploded globally, selling millions of copies under the toy giant Tsukuda Original (and later Milton Bradley).

The Digital Pioneer (1985–1990)

Because Reversi operates on simple, binary rule sets (a piece is either black or white, a move is either legal or illegal), it was an ideal candidate for early computer programming.

When Microsoft released Windows 1.0 in 1985, computer mice were a brand-new concept for everyday consumers. Microsoft needed a way to teach people how to use a mouse without writing a boring instruction manual.

They included Reversi as the built-in operating system game. It taught users the precise "point-and-click" spatial coordination required to operate a graphical interface. It held this prestigious default spot for years until Minesweeper dethroned it in Windows 3.1.

Legacy and AI Domination

Othello holds a unique place in the history of Artificial Intelligence. Because it has a smaller state-space complexity than Chess or Go, computers mastered it much faster.

In 1997, a computer program named Logistello completely dismantled the human World Champion, Takeshi Murakami, winning all six games in their match. Today, the game enjoys a robust international competitive scene, proving that a Victorian-era argument could evolve into an eternal test of strategic thinking.

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