⚫ Othello (Reversi)

Enjoy playing Othello against 2 players or against the CPU. Automatic highlighting of legal moves; CPU uses Greedy Law AI to ensure stone overturning strategy.

🌐 Online Battle
2
2
Your turn (black)

treatment

  • The translucent circle on the green board is where you can place it.
  • Place stones by clicking on where they can be placed
  • If you pinch an opponent's stone vertically, horizontally or diagonally, the stone will be turned over!
  • In CPU games, black (you) is the first player and white (CPU) is the second player.
  • If there is no place to put it, it will automatically pass.

What is Othello (Reversi) Web?

Othello, also called Reversi, is a classic strategy board game played on an 8×8 grid with 64 two-sided pieces. Players alternate placing pieces to capture opponent pieces and flip them to their own color. Legal moves are moves where a new piece creates a continuous line toward existing pieces of the same color, trapping opponent pieces between them. This web version lets you play against another person or challenge an AI opponent using a greedy algorithm. Despite simple rules, Othello offers surprising depth and competitive strategy.

How to Use

The board displays legal moves automatically—look for highlighted squares where you can play. Click or tap a legal square to place your piece. The game automatically flips all opponent pieces that become trapped between your new piece and existing pieces of your color. If you have no legal moves, the turn passes to your opponent. The game ends when neither player can move. Your score is the count of pieces in your color at game end; the player with more pieces wins. When playing the AI, the computer selects moves that maximize immediate piece captures. The interface shows the current board state, whose turn it is, and current scores.

Use Cases

Strategy game enthusiasts value Othello for its elegant simplicity masking genuine tactical complexity—early moves impact the endgame significantly. Casual players enjoy quick matches lasting 10–15 minutes, making it ideal for coffee breaks or waiting periods. Competitive players practice against the AI to develop strategy before tournament play. Teachers introduce Othello in classrooms to teach game theory, strategic thinking, and forward planning without overwhelming complexity. International communities appreciate Othello as a universal game—identical rules worldwide, making it a bridge across language barriers. Players learning AI design study the computer opponent to understand decision-making algorithms and heuristics.

Tips & Insights

Control the board's edges and corners—pieces there are harder to flip, providing stability. Early-game strategy differs from endgame: begin by limiting opponent options rather than maximizing immediate captures. Mobility matters more than piece count in mid-game; having more legal moves than your opponent provides a significant advantage. The opposite corners are particularly valuable; once secured, they're nearly impossible to flip. Late-game tactics shift toward efficiency: winning sometimes requires sacrificing pieces to limit your opponent's final moves. Study opening patterns from othello literature to develop a stronger strategic foundation.

Frequently Asked Questions

What are the rules?

If you place a stone between your opponent's stones, all stones in between are turned over. Finally, the player with more stones wins.

How strong is the CPU?

With the Greedy Method AI, choose the move that can turn over the most stones at once. Ideal for beginner practice.

What is a pass?

If there is not a single place where it can be placed, it will automatically pass.

What are the conditions for game termination?

The game ends when the board is filled or when there is no more room for both players.

Does this game have difficulty levels for the CPU opponent?

Yes, the CPU difficulty varies—you can choose easy, medium, or hard depending on your skill level. Harder difficulties use deeper look-ahead and better strategic evaluation to provide a competitive challenge.

Can I undo my moves if I make a mistake?

Most web versions include an undo feature that lets you take back your last move or several moves in sequence. This is helpful for learning and experimentation, though some versions may disable undo for competitive play.

How does the flipping mechanic work when I place a disc?

When you place a disc, all opponent discs in straight lines (horizontal, vertical, or diagonal) between your new disc and another of your color are flipped to your color. A move is valid only if it flips at least one opponent disc.

What should I do if I'm forced to pass my turn?

A pass is automatic when you have no valid moves. If your opponent also has no moves, the game ends immediately. To avoid passes, try to maintain mobility and avoid creating blocked positions on the board.

Are there opening strategies that work well for beginners?

Focus on corner and edge positions, avoid the squares next to corners (C-squares) early on, and prioritize mobility over disc count. Keeping your options open and controlling the board's center-edges is more important than accumulating discs quickly.

How do I know if I've won the game?

The game ends when neither player can move legally. The winner is whoever has more discs on the board in their color. The final score is displayed, showing the exact disc count for both players.