Reversi (Othello)

About Reversi (Othello)

Reversi is a classic strategy board game that combines tactical thinking with spatial awareness. Two players compete on an 8x8 board, placing dual-colored discs to capture and convert their opponent's pieces. The elegance lies in the flipping mechanic: when you trap enemy discs between your pieces, they flip to your color. What seems like domination can reverse in a single move, giving the game its apt name.

Though the basic rules can be learned in minutes, Reversi reveals surprising strategic depth. Beginners focus on capturing as many discs as possible, while experts understand that board position matters more than disc count until the endgame. The corners are king - once captured, they cannot be flipped and anchor your territory permanently. The interplay between immediate captures and long-term positioning creates a game that rewards both tactical vision and patience.

Our free online version pits you against a computer opponent that employs classic Reversi strategy. You play as Black, moving first, while the AI controls White. The interface highlights valid moves, making it easy to see your options. Whether you're learning the game or honing your strategy, our Reversi provides an engaging challenge that scales with your skill.

History of Reversi

Reversi was invented in Victorian England, with two men claiming credit independently around 1883: Lewis Waterman of London and John Mollett. The game quickly gained popularity, spreading throughout Europe and Japan. The original rules varied slightly from modern play - for instance, the starting position was empty, with players taking turns placing any disc in the center four squares.

The game was reinvented in 1971 by Japanese salesman Goro Hasegawa, who trademarked it as "Othello" after the Shakespeare play. Hasegawa standardized the starting position (the current diagonal arrangement) and promoted the game through tournaments. Othello became a phenomenon in Japan and eventually worldwide, with the World Othello Championship starting in 1977 and continuing annually to this day.

Reversi and Othello are essentially the same game with minor rule differences (Othello has the fixed starting position and Black moves first). The game has been extensively studied by computer scientists, with programs achieving superhuman play through algorithmic search and pattern recognition. Despite this analysis, the game retains its appeal for human players who enjoy the dramatic swings and strategic complexity.

How to Play Reversi

Follow these steps to master the art of disc-flipping strategy:

Step 1: Understand the Setup

The game begins with four discs in the center of the 8x8 board: two Black and two White, arranged diagonally. You play as Black, and the computer plays as White. Black always moves first in Othello rules.

Step 2: Make a Valid Move

Click any highlighted square to place your disc. A valid move must "outflank" at least one opponent disc - meaning your new disc creates a straight line (horizontal, vertical, or diagonal) with another of your discs, with one or more enemy discs in between. All outflanked discs immediately flip to your color.

Step 3: Watch for Multiple Captures

A single move can outflank discs in multiple directions simultaneously. When you place a disc, all opponent discs that are outflanked in any direction flip at once. Look for these "multi-directional" captures to maximize your gains.

Step 4: Plan for Position, Not Just Count

Counter-intuitively, having fewer discs in the midgame is often advantageous. More discs means more targets for your opponent to flip. Focus on securing good positions - especially corners and stable edges - rather than maximizing disc count until the endgame.

Step 5: Finish Strong

The game ends when neither player can make a valid move (usually when the board is full). The player with more discs wins. In the endgame, disc count finally matters - secure as many stable discs as possible while limiting your opponent's options.

Game Rules

Reversi has simple rules that create complex strategy:

Outflanking (Capturing)

You capture opponent discs by "outflanking" them. To outflank, place a disc that creates a straight line with one of your existing discs, with only enemy discs between them. The trapped discs flip to your color. You must outflank at least one disc per turn.

Multi-Directional Captures

A single placement can outflank discs in multiple directions - horizontal, vertical, and diagonal all at once. All outflanked discs in all directions flip simultaneously. This makes some moves devastatingly powerful.

Must Move If Possible

If you have any valid move, you must make one. You cannot pass when legal moves exist. Passing only occurs when no valid moves are available - in this case, your opponent continues playing until you can move again.

Game End Conditions

The game ends when neither player can make a valid move. This usually happens when the board is full, but can occur earlier if all remaining empty squares are invalid for both players. The player with more discs showing their color wins.

Discs Cannot Be Removed

Once placed, discs stay on the board until the game ends. They may flip colors multiple times, but the number of discs never decreases. The board fills progressively until 64 discs occupy all squares (or the game ends earlier).

Tips and Strategy

Elevate your Reversi game with these proven strategic principles:

Corner Control is Everything

Corners cannot be outflanked once captured. A corner disc remains your color for the entire game, providing a permanent anchor. More importantly, corners help you capture entire edges. Fight for corners and avoid giving them to your opponent.

Avoid the "X-Squares"

The diagonal squares adjacent to corners (called X-squares) are dangerous. Placing a disc there often gives your opponent access to the corner. Avoid X-squares unless you can immediately capture the corner yourself or unless no better option exists.

Edges After Corners

Edge squares become "stable" (unflippable) when you control the adjacent corner. A stable edge acts as a permanent wall for your territory. Build edges outward from corners you control to maximize your stable disc count.

Mobility Matters

Having more available moves than your opponent gives you flexibility. If your opponent runs out of moves, you play multiple turns in a row, potentially setting up devastating positions. Don't trap yourself by taking moves that leave you with few options.

Keep Your Opponent Crowded

Paradoxically, having fewer discs in the midgame can be advantageous. Each of your discs is a potential target. Fewer, well-placed discs leave your opponent with limited targets and bad options. Let your opponent build up a large but unstable position.

Think About the Endgame

In the final 10-15 moves, the dynamics shift. Now disc count matters, and you should maximize captures. The player with good corner and edge control can often sweep the endgame, flipping dozens of discs in the final moves.

Frequently Asked Questions

Is Reversi free to play online?

Yes, our Reversi game is completely free with no registration, downloads, or hidden costs. Simply load the page and start playing against the computer immediately. Games take 5-15 minutes and you can play as many as you like.

What's the difference between Reversi and Othello?

They're essentially the same game with minor differences. Othello uses a fixed starting position (four discs in the center as in our game) and always has Black move first. Original Reversi had players place the initial four discs anywhere in the center and could have either color move first. Most modern play uses Othello rules.

Can I play against another person?

This version is designed for single-player against the computer. You play as Black, and the AI controls White. The computer uses classic Reversi strategy, prioritizing corners and edges while maintaining mobility.

How strong is the computer opponent?

Our AI uses solid positional strategy - it prioritizes corners, values edges, and maximizes captures when other factors are equal. It provides a good challenge for beginners and intermediate players. Experienced players may beat it consistently but will still find it a reasonable opponent.

Why did my discs flip when it wasn't my turn?

When the computer (White) makes a move, it outflanks your Black discs, which then flip to White. This is normal gameplay. The dramatic swings in disc count are what make Reversi exciting - a position can reverse completely in just a few moves.

Why can't I place a disc in certain squares?

You can only place discs where they outflank at least one opponent disc. Empty squares that don't create any outflanking are invalid moves. The highlighted squares show all your legal options. If no moves are highlighted, you have no valid moves and must pass.

Why did my turn skip?

If you have no valid moves, your turn is automatically skipped and the computer plays again. This can happen multiple times in succession. The game only ends when neither player can move.

How do I win at Reversi?

Have more discs showing your color when the game ends. Focus on controlling corners and edges rather than maximizing disc count early. In the endgame, capture as many discs as possible while limiting opponent options.

Can I play Reversi on my phone?

Yes, our Reversi is fully responsive and works perfectly on smartphones and tablets. Touch controls work naturally for selecting moves. No app download is required.

Why do corners matter so much?

Corner discs can never be outflanked - they remain your color permanently once captured. They also anchor edges, making entire rows and columns stable. A player who controls 3-4 corners usually wins convincingly.

What are "stable" discs?

Stable discs cannot be flipped for the rest of the game. Corner discs are always stable. Edge discs become stable when connected to a corner of your color. The goal is to maximize stable discs, as they represent guaranteed final score.

Is Reversi harder than Chess?

They're different types of challenges. Reversi has simpler rules and fewer possible positions than Chess, making it easier to analyze. However, Reversi's "flipping" mechanic creates unique strategic considerations. Computers have "solved" Reversi more completely than Chess, but both games remain enjoyable for human players at all skill levels.