How to Play Reversi
Reversi (also known as Othello) is a strategy game played on an 8x8 board with two-sided discs -- black on one side, white on the other. The game starts with four discs in the center. On your turn, place a disc so that it traps one or more of the opponent's discs between your new disc and an existing one of yours, in any straight line. All trapped discs are flipped to your color.
If you cannot make a valid move, you pass. The game ends when the board is full or neither player can move. The player with the most discs on the board wins. On PlayVersusAI, you play as black and go first.
Strategy Tips
- Fight for corners -- Corner discs can never be flipped. They anchor your position and control the board.
- Avoid X-squares and C-squares -- The squares diagonally adjacent to corners (X-squares) and directly adjacent (C-squares) can give your opponent the corner. Stay away from them when the corner is empty.
- Keep disc count low early -- Counter-intuitively, having fewer discs in the early game gives you more moves. This is called disc minimization.
- Maximize mobility -- Try to have more legal moves available than your opponent. When they run out of good moves, they're forced into bad ones.
- Think about stable discs -- Discs that can never be flipped (edges, corners, lines connected to corners) are your most valuable assets.
Read the full Reversi guide →
Playing Reversi on PlayVersusAI
Reversi, often sold under the name Othello, is played on an 8x8 board that starts with four discs in the middle. Every move must sandwich at least one line of your opponent's discs between the piece you place and another of your own, and every disc caught in that sandwich flips colour. If you have no legal sandwiching move you must pass. The game ends when neither side can move, and the player with more discs wins.
What makes Reversi unusual is that being ahead is often bad. A player holding forty discs in the midgame typically has very few legal moves available, and running out of options means being forced into a move that hands over a corner. Our engine understands this: for most of the game it almost ignores disc count and optimises for mobility and corner safety instead, which is why it can look like it is losing badly right up until it isn't.
What's on This Page
- Four difficulty levels — switch between Easy, Medium, Hard and AI Training at any time, including mid-game.
- Built-in tutorial — an illustrated, step-by-step walkthrough of the rules on the board itself, via the How to Play button.
- Coach mode — live move analysis while you play, plus a full post-game review that marks where the game actually turned.
- Online multiplayer — play a friend in real time using a private room code, or take on a stranger from the public lobby.
- Tracked results — wins count toward your profile statistics and the site leaderboard.
- No account required — the full game is playable as a guest, on desktop, tablet or phone.
Easy grabs discs greedily, which is exactly the mistake beginners make, so it is a fair fight while you learn. Medium starts valuing position over count. Hard plays the corner game properly and will refuse tempting captures. AI Training combines deep search with a late switch to exact disc counting in the endgame, and it is extremely hard to out-manoeuvre once it owns two corners.
Mistakes That Lose Games
- Flipping as many discs as possible every turn. This is the single biggest beginner error. Maximum flips in the midgame usually means minimum mobility a few moves later.
- Playing a square diagonally adjacent to an empty corner. These squares hand the corner to your opponent more reliably than almost any other move on the board. Avoid them until the corner is settled.
- Taking edges for granted. Edge discs cannot be flipped from the side, but an unsupported edge run can be attacked from the end and turned into a liability rather than an anchor.
- Panicking at a low disc count. Being down twenty discs with twelve moves left is often a winning position. Count your legal moves, not your pieces.
Reversi Questions
Is this the same game as Othello?
Yes, in all the ways that matter to play. Othello is the trademarked commercial version of Reversi, standardised with a fixed starting position of four central discs — which is what this implementation uses.
Why was I forced to skip a turn?
Because you had no legal move. Every move in Reversi must flip at least one opposing disc, and if no such move exists the turn passes back automatically. Having no moves is usually a warning sign that your mobility has collapsed.
Why does the AI give away so many discs early?
Deliberately. Holding few discs in the midgame keeps its options open and restricts yours. The engine values mobility and corner control far above disc count until the very end of the game, when it switches to counting exactly.
For the complete rules, the deeper strategy and the history of the game, read the full Reversi guide, or browse guides for all 20 games.