Othello (also called Reversi) is a two-player abstract strategy game on an 8×8 board. Each side has 64 disks white-on-one-side and black-on-the-other. Players alternate placing disks; any disks flanked between two of your color flip to your color. Whoever has the most disks of their color when the board fills wins.
Each turn, place one disk on any empty square that flanks at least one enemy disk (in any direction — horizontal, vertical, or diagonal) between your new disk and another of your existing disks. All flanked enemies flip. If you have no legal placement, you pass. Game ends when neither side can move.
Othello takes minutes to learn; chess years. Othello games typically end in 60 moves; chess can stretch hundreds. Othello also features the famous "mobility paradox" — having many pieces early is often a disadvantage.
Counterintuitively, prefer to have FEWER disks early. More disks reduce your move options and give opponent more flanking targets. Aim for "quiet" central play; corners and edges become decisive in the endgame.
8×8 Othello is not yet weakly solved (as of 2026), but engines play above all-time human champion level. 6×6 was weakly solved in 1993 (draw with perfect play).
Corners are permanent (can never be flipped). Avoid giving your opponent access to a corner; squares adjacent to corners ("X-squares") often hand the corner to opponent if you play them early.
Othello — also known as Reversi — is a two-player disc-flipping game on an 8×8 board. It takes a minute to learn and years to master: the rules are trivial, but the strategy is deep enough that top play looks almost paradoxical. This guide covers the rules and the handful of ideas that will beat a casual opponent or the browser AI.
New players flip as many discs as possible every turn. This loses. Because any disc can be flipped again later, a big early lead means nothing — and having more discs mid-game often means you have fewer safe moves. The real currency of Othello is not discs; it is stable squares and mobility.
A disc in a corner can never be flipped — there is no square beyond it to flank from. Corners anchor entire edges and rows of stability. The whole game is really a fight to take corners and to force your opponent into giving them to you.
The square diagonally adjacent to a corner (the X-square) is the most dangerous square on the board — playing there early usually hands your opponent the corner. The squares orthogonally next to a corner (C-squares) are risky for the same reason. Leave the region around empty corners alone until you can take the corner itself.
Good Othello players try to have many moves while their opponent has few. Fewer discs of your own, placed compactly in the center early on, often gives you more flanking options later. If your opponent runs out of safe moves, they are forced to play an X-square or C-square and surrender a corner. Aim to end the midgame with your opponent nearly out of good options.
If you like the pure-abstract tension of Othello, Go (see the beginner’s guide) rewards the same territorial thinking on a bigger canvas, and Chess scratches the tactical itch.