Othello Strategy: How to Win
You can learn the rules of Othello (also known as reversi) in a minute, yet beginners regularly flip half the board early on and still lose by a wide margin. That's because winning isn't about how many discs you have right now; it's about how many good moves you'll have later. This guide covers corners, the dangerous squares next to them, mobility, stable discs, and endgame parity, in the order you'll actually need them.
The board is almost empty. White at the a1 corner flips one black disc. White at a5 flips five black discs on that rank. Flipping more is not automatically a trap. Each difficulty played this position 30 times.
Start
a1 brackets one black disc against the white disc beside it. a5 is the left end of five black discs, so it flips all five. Both squares are legal. Ranks are numbered from the top, as on an Othello board.
Line 1 / 4
The left board is Normal, which trusts the square values. The right board is Hard, which scores the whole position. Both moves are legal, and neither was a blunder here.
Normal 30/30
Corners are worth 120 on the value table. The X-square diagonal to a corner is −40. Normal adds flipped discs to that value and takes the corner.
Hard 30/30
If more than 16 squares are empty Hard reads 2 plies, 3 plies at 16 or fewer, and 5 plies at 10 or fewer. This opening is a 2-ply search, and the larger disc swing won.
The same discs, 30 calls per difficulty. Only Easy mixed the two moves.
11 Oct 2026: Playfulo's Othello AI, 30 calls per difficulty on this position. Easy's random window means the '3 trials' count can change. Square weights and search depth are the engine's values.
Othello is played on an 8×8 board. The game begins with four discs in the center, two black and two white placed diagonally, and Black moves first. You place a disc so that one or more opponent discs are sandwiched in a straight line, horizontally, vertically, or diagonally, between your new disc and one of yours. Every sandwiched disc flips to your color.
A move is legal only if it flips at least one disc; if you have none, you pass. The game ends when neither player can move or the board is full, and whoever has more discs on the board wins. Playfulo's Othello follows these standard rules, and empty squares don't count toward anyone's score.
Strategy writers usually borrow chess notation: columns a to h from left to right and rows 1 to 8 from top to bottom. In that system the four corners are a1, h1, a8 and h8, and that's the notation used below.
A corner disc can never be flanked from both sides, so once it's placed it stays your color for the rest of the game. Better still, discs you connect to it along the same edge also become impossible to flip. A single corner often becomes the anchor for an entire edge and much of the area around it.
You can't simply take a corner whenever you like. It only becomes a legal move when an opponent disc sits next to the corner with one of your discs beyond it. So the real corner battle isn't about grabbing corners yourself; it's about maneuvering your opponent into playing next to them.
Taking a corner doesn't automatically win the game, either. Sometimes grabbing one corner hands over two others, or opens up a pile of new moves for your opponent. If a corner is available and your opponent has no way to take the option away, it will still be there later, so it can pay to play a more urgent move first.
The squares diagonally adjacent to the corners (b2, g2, b7, g7) are called X-squares. Put a disc there while the corner is empty, and you often hand your opponent a diagonal line straight into that corner. Playing an X-square early is one of the most common and costly mistakes in the game.
The squares next to a corner along the edge (a2, b1, g1, h2, a7, b8, g8, h7) are C-squares. They can also give away a corner along the edge, but they're more situational than X-squares. If the discs on that edge are arranged so your opponent can't reach the corner, a C-square can be perfectly safe.
Once you own a corner, the X- and C-squares beside it stop being dangerous. Always judge these squares by asking: is the neighboring corner still empty, and who could take it next?
Mobility is the number of legal moves available to you. The more options you have, the easier it is to find a good one; when your options run out, you're forced into X-squares, C-squares, or giving up edges. Strong players spend the opening and middle game increasing their own mobility and squeezing their opponent's.
That leads to a counterintuitive principle. Flipping lots of discs early spreads your color across the board and gives your opponent more targets and more legal squares. Keeping fewer discs, clustered toward the center, limits their choices. In the early game, the player with fewer discs is frequently the one doing better.
Frontier discs are discs that border an empty square. Each one is a potential target, because your opponent can play into that empty square and flip it. Prefer quiet moves that flip interior discs and open up as few new empty-square contacts as possible, rather than moves that push your discs outward.
Edge discs are harder to flip than central ones, but while the corners on that edge are empty, they can still be taken. When you move onto an edge, think about who will eventually claim both of its corners. Rushing to fill an edge is a classic way to open a path into the corner for your opponent.
Stable discs are discs that can't be flipped for the rest of the game: an unbroken run from a corner along an edge, or discs that can no longer be flanked from any direction. From the middle game on, the number of stable discs you can add usually matters more than how many discs a move flips right now.
Parity is about who gets the last move. The final move flips discs with no chance of a reply, so it's usually an advantage. Without passes, if an even number of empty squares remains, your opponent will make the last move rather than the player about to move, which is why counting empty squares matters in the endgame.
In real games the empty squares split into several small regions. Playing first into a region with an odd number of empties tends to let you take the last move there. Leaving a region your opponent can't legally enter forces them to pass, which gives you consecutive moves.
Once about ten empty squares remain, reading out each candidate move is the most reliable approach. For every option, check where your opponent can reply and whether any corner or edge changes hands.
In the opening, stay quiet inside the central 4×4 area. Black's first move is symmetrical, so all four options are effectively the same, but White's reply splits the game into what players call diagonal, perpendicular, and parallel openings. More important than the names is the habit of not reaching for the edges early and choosing moves that leave your opponent few options.
Most beginner mistakes come from wanting to flip as much as possible right now. Greedy early moves widen your opponent's options, until you run out of safe squares and have to play into danger. Remember that the disc count can swing dramatically in the last handful of moves.
On Playfulo you can play Othello against AI on easy, normal, or hard. Use easy to practice avoiding X-squares and setting up corners, move to normal while consciously tracking mobility, then take on hard. To play a friend, create a room and share the invite link.
No move sequence wins every game, but the winning principles are clear: take corners, avoid the X- and C-squares next to empty corners, and flip few discs early so your opponent has fewer legal moves. In the endgame, count the empty squares and aim to make the last move in each region.
Usually, yes. Flipping many discs spreads your color out and gives your opponent more discs to flank and more squares to play. Flipping fewer and staying compact in the center limits their options and can force them into dangerous squares.
X-squares are b2, g2, b7 and g7, diagonally next to the corners. C-squares are a2, b1, g1, h2, a7, b8, g8 and h7, beside the corners along the edges. Playing them while the adjacent corner is empty often gives that corner to your opponent; once you own the corner, they're no longer dangerous.
They're the same family of game: both are played on an 8×8 board by flanking and flipping opponent discs. Othello usually refers to the version with a fixed four-disc starting position and Black moving first. Playfulo's Othello follows those standard 8×8 rules.