Reversi OK: rules, AI levels and strategy tips

Reversi OK is the classic disc-flipping game on a glossy 8×8 board. Play against the AI or hand the device to a friend. It runs in your browser and is available on iPhone, iPad and Android.

The rules in one minute

• The board starts with four discs in the centre. You play Black and move first.
• Place a disc so that one or more of your opponent's discs lie in a straight line — across, down or diagonally — between your new disc and another of yours.
• Every trapped disc flips to your colour. One move can flip several lines at once.
• Legal moves are highlighted. If you have none, your turn passes.
• The game ends when neither player can move, and whoever has more discs wins.

Choosing an AI level

• Easy is forgiving: good for learning the rules and testing ideas.
• Normal plays solid moves and punishes obvious mistakes.
• Hard fights for corners, edges and mobility, and plays the endgame perfectly once few squares are left.
• Master is a hidden level that unlocks after 100 wins in total. Hint and Undo are switched off there.

Against the AI, Hint suggests a move and Undo takes back your move and the AI's reply. Each win adds to your career score, and harder levels count more (Easy ×1, Normal ×2, Hard ×3, Master ×4). Career points are just for fun: they can't be bought or exchanged. The online leaderboard lists real players only; AI results never appear on it.

Two players, one device

Pick the two-player mode and take turns as Black and White. The board shows whose turn it is and updates the disc count after every move.

Strategy that works

• Take the corners. A disc in a corner can never be flipped.
• Stay off the squares next to an empty corner, especially the diagonal one. They often hand the corner to your opponent.
• Mobility beats material. In the middle of the game, having more possible moves matters more than having more discs. Grabbing lots of discs early often leaves you with few safe moves later.
• Play quiet moves that flip few discs and leave your opponent short of options.
• Use Undo to learn. Against Easy or Normal, when a move turns out badly, undo it and try the alternative to see what changes.

Where to play

Visit the Reversi OK page for screenshots, or play now in your browser. The store buttons below always show where the game is live today.