How to Play Reversi (Othello) — Free Online Rules & Strategy

To play Reversi — the same game sold as Othello — you and your opponent take turns placing discs on an 8×8 board. Every move must trap at least one straight line of your opponent’s discs between the disc you just placed and another disc of yours; every trapped disc flips to your color. If you have no legal move, you pass. The game ends when the board is full or neither side can move, and whoever owns more discs wins. The rules take a minute to learn, but the strategy is famously counterintuitive: grabbing lots of discs early usually loses, while quietly taking corners and limiting your opponent’s options usually wins. You can play it free in your browser against the computer, with no download and no sign-up, at Offline Games Arcade.

The rules in one minute

The board is 8×8, and it starts with four discs. Two black and two white sit diagonally in the four center squares.
Black moves first. Players then alternate.
Every move must flip something. You can only place a disc where it brackets one or more of your opponent’s discs in a straight line — horizontally, vertically, or diagonally — with another of your discs at the far end.
Flip every line you bracket. If one placement traps discs in several directions at once, all of them flip.
No legal move means you pass. Your turn is skipped and play goes back to your opponent. You can’t pass voluntarily if a legal move exists.
The game ends when nobody can move. That’s usually when all 64 squares are full, but it can happen earlier if neither side has a legal placement.
Most discs wins. Equal counts is a tie.

The one rule that trips up new players is the “must flip” rule. You can’t drop a disc anywhere you like — only on squares that capture. That single constraint is where all of the game’s strategy comes from, because a position where your opponent has few legal moves is a position where they are forced into bad ones.

Playing Reversi on Offline Games Arcade

Our version of Reversi is a one-player game against the computer. You play Black and always move first; the CPU plays White. A few details make it friendly for learning:

Legal moves are marked with dots. You don’t have to scan the board for captures — tap any highlighted dot to place your disc, and every bracketed disc flips automatically.
Three difficulty levels. You pick Easy, Medium or Hard when you first start, and you can switch later.
Passes are handled for you. If either side has no legal move, a pass banner shows and play continues.
Separate records per level. The game keeps your wins, losses and ties for each difficulty, so you can track progress as you move up.
Your game is saved. Close the tab mid-game and your position is still there when you come back.

It also works offline in the free Offline Games Arcade app for iPhone and Android, so a flight or a dead zone doesn’t stop a game.

Strategy 1: corners are permanent

A disc in a corner can never be flipped, because there is no square beyond it to bracket it from. Better still, a corner disc anchors the two edges next to it: discs you add along those edges, touching the corner, become permanent too. Most Reversi games between decent players are decided by who ends up owning the corners.

So the first strategic habit is simple: when a corner is legal for you, take it unless you can see a clear reason not to.

Strategy 2: stay off the squares next to corners

The flip side of corner value is that the squares touching a corner are dangerous. The diagonal square next to each corner (often called the X-square) is the worst: if you put a disc there early, you often hand your opponent a legal move into the corner. The two edge squares beside each corner (the C-squares) carry the same risk, a little less directly.

A good rule of thumb for beginners:

Don’t play an X-square while that corner is empty, unless it’s the only legal move you have.
Treat C-squares with suspicion in the opening and midgame.
Once a corner is taken, its neighbors are safe to play — the danger is gone.

Strategy 3: fewer discs, more moves

This is the idea that surprises everyone. In the midgame, having fewer discs is often better. Why? Every one of your discs on the board is a potential target, and more importantly, every disc of your opponent’s gives you something to flip. If you hold most of the board, your opponent has lots of legal moves and you have very few. Eventually you’re forced to play into an X-square or give up an edge.

Strong players think in terms of mobility — how many legal moves each side has. Moves that flip only one or two discs, especially interior discs, tend to keep your options open and restrict your opponent’s. Moves that flip a huge line across the board often look great on the scoreboard and then collapse ten moves later. Our game description says it plainly: the player leading at midgame often loses.

Strategy 4: avoid frontier discs

A frontier disc is one that sits next to an empty square. Frontier discs are exposed — they’re what your opponent will flip next. Interior discs, surrounded by other discs, are harder to attack and don’t give your opponent new places to move.

When you’re choosing between two legal moves, prefer the one that flips discs in the middle of the pack rather than the one that creates a long wall of your color facing open space. It’s the same idea as Strategy 3 from a different angle: don’t hand your opponent targets.

How to beat each difficulty level

The CPU plays noticeably differently at each level, so the best approach changes as you move up.

Easy

On Easy, the computer picks among its legal moves at random. It doesn’t prefer corners and doesn’t avoid X-squares, so it will regularly give corners away. This is the right level for learning the rules: watch for the moment a corner becomes legal for you, take it, and then build along that edge. Practice keeping your disc count modest in the midgame even when you don’t need to — it’s a habit you’ll want later.

Medium

On Medium, the computer greedily picks the move that flips the most discs right now. That makes it look strong in the opening, because it often leads on the scoreboard. It’s also its weakness: a greedy player happily grabs big lines that leave it with poor mobility and happily plays next to corners if that flips the most discs. Let it take the disc lead, keep your own moves quiet, and wait. When it runs short of good moves, it will open a corner for you.

Hard

On Hard, the computer looks three moves ahead and scores positions with a board map that rewards corners and edges and penalizes the squares next to corners. It won’t give corners away cheaply, so basic tricks stop working. To beat it, lean on the ideas it doesn’t measure as directly: keep your mobility high and its mobility low, avoid frontier discs, and try to create positions where its only legal moves are bad ones. Plan for the endgame too — when a few empty regions remain, count who will get the last move in each one.

Common beginner mistakes

Maximizing flips every turn. It feels productive, but it drains your future options.
Playing an X-square early and watching the opponent take the corner next turn.
Rushing to fill edges. An edge that isn’t anchored by a corner can often be flipped back.
Forgetting diagonals. A single placement can capture in up to eight directions; check them all before you commit.
Giving up when behind. Disc counts swing wildly near the end. A game that looks lost at move 40 can flip in the last few moves.

If you like Reversi, try these

Reversi sits in a family of short, deep abstract games. If you enjoy it, these are worth a look:

Chess — the classic of long-term planning and piece coordination.
Checkers — captures and forced jumps reward the same “look ahead” thinking.
Four in a Row — building threats on a grid, in a few minutes per game.
Mancala — another counting-and-tempo game where the obvious move isn’t always best.
Dots and Boxes — like Reversi’s endgame, it’s all about who is forced to move first.

You’ll find all of them, plus the rest of the collection, on the board games page.

FAQ

Is Reversi the same as Othello? Yes. Othello is a trademarked version of Reversi that uses the same 8×8 board, the same four-disc starting position, and the same flipping rules. If you know one, you know how to play the other.

What happens if I have no legal move in Reversi? Your turn is skipped and your opponent moves again. If neither player can move, the game ends immediately and the discs are counted.

Why are corners so important in Reversi? A disc in a corner can never be flipped, and it makes the adjoining edge discs safer. Whoever controls more corners usually controls the end of the game.

Should I try to flip as many discs as possible? Usually not in the opening and midgame. Keeping fewer discs and more legal moves tends to leave your opponent with bad choices later. Maximizing flips makes more sense in the final few moves, when the count is what decides the game.

Can I play Reversi free without downloading anything? Yes. Reversi runs in your browser on Offline Games Arcade with no download or sign-up, and it’s also in the free Offline Games Arcade app if you want to play offline.

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