How to Play Reversi (Othello) — Strategy Guide & Winning Tips

What Is Reversi (Othello)?

Reversi — marketed as Othello since 1971 — is a two-player strategy game played on an 8×8 board with double-sided discs that are black on one side and white on the other. Players take turns placing discs on the board, and any opponent discs caught between the new disc and an existing friendly disc are flipped to your color.

The name "Othello" (trademarked by Mattel) comes with the tagline "a minute to learn, a lifetime to master," which perfectly captures the game. The rules take seconds to explain, but the strategy runs deep — world-class players study Othello theory with the same intensity as chess.

At the end of the game, the player with more discs on the board wins. But here's the paradox that defines Othello strategy: having fewer discs during the game is usually better than having more.

The Rules

1. Setup: The game starts with four discs in the center — two black and two white — placed diagonally.
2. Placement: On your turn, place a disc on an empty square such that it outflanks at least one opponent disc. "Outflank" means your new disc and an existing disc of your color form a straight line (horizontal, vertical, or diagonal) with one or more opponent discs between them.
3. Flipping: All outflanked discs are flipped to your color. A single move can flip discs in multiple directions simultaneously.
4. Passing: If you have no legal moves, you pass. If both players pass consecutively, the game ends.
5. Winning: When the board is full (or both players pass), count the discs. The player with more discs wins.

One critical rule that beginners miss: you must outflank at least one disc on every move. You can't place a disc on an arbitrary empty square — it must create at least one flip.

The Corner Is King

The four corner squares are the most valuable positions on the board, and virtually all Othello strategy revolves around them.

Why corners matter: Once placed, a corner disc can never be flipped — there's no square beyond the corner to outflank from. A corner disc is permanent, and it anchors your control of the surrounding edges and diagonals.

How to get corners:

• Don't play adjacent to corners (the "X-squares" and "C-squares"). The squares diagonally adjacent to corners (X-squares) are the most dangerous on the board. Playing there gives your opponent a direct path to the corner. The squares directly adjacent (C-squares) are less dangerous but still risky in the early and middle game.
• Force your opponent onto X-squares. Through careful play, reduce your opponent's options until they're forced to play next to a corner. Then seize it.
• Corner timing: Don't just take a corner because it's available — take it when it flips the maximum number of discs or when the resulting position is strong. Sometimes delaying a corner capture is correct if it lets you set up a better sequence.

Edge Play: Stable Discs and Wedges

The edges (the outer rows and columns) are the second most important area after corners. Edge discs adjacent to a corner are stable — they can't be flipped because there's nothing beyond the edge to outflank from (as long as the chain is unbroken to the corner).

Building stable edges: Once you capture a corner, extend your discs along the edge from that corner. Each disc in an unbroken line from the corner is stable. A full stable edge (8 discs from corner to corner) is devastating — those 8 discs can never be lost.

The wedge: A wedge is when you place a disc between two opponent discs on an edge, flipping one or both. Wedges on edges are powerful because they break your opponent's edge control and can give you access to corners. Look for wedge opportunities, especially when your opponent has a long unanchored edge.

Unbalanced edges are dangerous: If you have five discs on an edge but don't control either corner, your opponent can potentially flip the entire edge with a single well-placed move. Edge control without corner control is fragile.

Mobility: The Counter-Intuitive Key to Winning

Here's where Othello strategy diverges from common sense. You want to have fewer discs than your opponent during the middle game. This is called disc minimization, and it works because of mobility.

Mobility is the number of legal moves available to you. More legal moves means more choices, and more choices means a better chance of finding a move that doesn't give up a corner or edge.

How disc minimization creates mobility: Every disc you have on the board is a disc your opponent can potentially flip — and every flip creates a new legal move for you. If you have 10 discs and your opponent has 30, they have very few discs to flip (only your 10), giving them fewer legal moves. Meanwhile, you have 30 of their discs as potential flip targets, giving you many options.

In practice:

• Prefer moves that flip few discs, not many. Flipping a single disc is often better than flipping six.
• Avoid moves that create a large, expansive "frontier" (exposed discs on the border of your territory). Frontier discs give your opponent move options.
• Aim for moves that are "quiet" — they flip interior discs rather than expanding your frontier.

Tempo and Passing

Tempo is the rhythm of who's forcing whom. In Othello, having tempo means your opponent is forced into bad moves while you dictate the board position.

One of the most powerful tempo plays is forcing your opponent to pass. If your opponent has no legal moves, they pass and you play again — potentially playing two or three consecutive moves to set up a devastating sequence.

How to create pass situations:

• Reduce your opponent's frontier discs (the ones you can flip against). If you leave them no legal outflanking moves, they must pass.
• Play in regions of the board where your opponent has no presence. If all their discs are on one side and you play on the other, they might not be able to reach any empty squares.

Conversely, avoid being passed yourself. Keep at least a few discs spread across the board so you always have legal moves available. Being forced to pass hands the game's momentum to your opponent.

The Opening: First 20 Moves

Othello openings have been deeply studied, and named lines exist (the "tiger," the "rose," the "buffalo"). For most players, understanding the principles is more useful than memorizing specific sequences:

• Play toward the center, not the edges. In the opening, edge moves give your opponent footholds near corners. Central play keeps options open.
• Minimize your disc count. Early flips that take lots of territory feel good but give your opponent mobility. Flip as few discs as possible.
• Keep your discs compact. A tight cluster with minimal frontier exposure is harder for your opponent to exploit than a sprawling line.
• Watch the diagonals. The main diagonals (corner to corner) are highways. If your opponent establishes a strong diagonal, they can leverage it to reach corners.

The opening typically lasts about 20 moves (roughly one-third of the game). By the end of the opening, the strategic landscape is usually set — you're either fighting for corners and mobility or scrambling to recover.

The Endgame: Counting and Parity

The endgame (roughly the last 10–15 moves) is where Othello transforms from a strategic game into a counting game. At this point, the board is mostly filled, and the question is: will this sequence of moves leave me with more discs?

Exact counting: In the endgame, calculate the disc difference for each possible move. If move A leaves you +4 and move B leaves you +2, play move A. Top players can count the endgame perfectly from about 15 empty squares remaining.

Parity: The most important endgame concept. If there are an even number of empty squares in a region, the player who moves second in that region gets the last move. In many endgame positions, getting the last move means flipping discs that your opponent can't flip back.

How to use parity:

• Count the empty regions on the board and their sizes (odd or even).
• If possible, let your opponent move first in even-sized regions so you get the last move there.
• Play into odd-sized regions yourself to seize the last move.

Parity doesn't override everything — a move that gains a corner is almost always better than one that optimizes parity. But when the positions are otherwise close, parity decides the game.

Common Mistakes

• Maximizing discs early: The #1 beginner mistake. Having 40 discs at move 30 means nothing if your opponent takes all four corners and flips 20 of them in the last 10 moves. Focus on position, not disc count.
• Playing X-squares (diagonal to corners): Unless you can guarantee the adjacent corner, playing an X-square almost always gives the corner to your opponent. This is the most punished mistake at all levels.
• Ignoring mobility: If you have only 2 legal moves and your opponent has 12, you're in deep trouble regardless of disc count. Always consider how your move affects both players' mobility.
• Neglecting the endgame count: Switching from strategic play to exact counting is a skill that must be practiced. Start counting from 10 empty squares and work up to 15-20.
• Claiming edges without corners: An edge you don't anchor from a corner can be catastrophically flipped. Secure the corner first, then extend along the edge.

Improving Your Game

Othello rewards focused practice more than almost any other board game. Here's how to improve efficiently:

• Study your losses. After every game, identify the move where things went wrong. Was it an X-square? A move that gave your opponent too much mobility? An endgame miscount? Each loss should teach one lesson.
• Practice endgame counting. Set up positions with 10 empty squares and try to calculate the optimal sequence. This is a skill that transfers directly to real games.
• Play the "quiet" game. For your next ten games, make a conscious effort to flip as few discs as possible on every move. This forces you to play for mobility and position instead of territory.
• Learn one opening well. Pick a response to the standard first move and study it deeply. Understanding one opening thoroughly teaches you principles that apply everywhere.