A free reversi game against the computer

Reversi is free to play in Games by Zaweba, in a game called Flip Discs. You play black against the computer, placing discs to trap lines of white ones and flip them to your colour, and whoever has more discs when neither side can move wins. It runs offline, with no adverts and no account.

Reversi takes a minute to learn and a long time to play well. The board can swing from one colour to the other in a few moves, which keeps every game tense right to the end.

The rules of Flip Discs

You play black and move first. Place a disc so that it traps a straight line of white discs between it and another black disc, in any direction. Every disc you trap flips to black. If you can't make a move that flips something, you have to pass. When neither side can move, the player with more discs wins.

The game helps you see what's possible. You click a glowing square to place a disc, so legal moves are always shown, and hovering over a square shows which discs would flip. Flip Discs is on the Board games shelf of Games by Zaweba.

Why the corners matter

A disc in a corner can never be flipped, because there's nothing beyond it to trap it against. That makes corners the most valuable squares on the board. A corner also tends to anchor whole edges that can't be taken back.

The squares right next to a corner are the dangerous ones. Placing a disc there can hand the corner to your opponent. Early on, try to avoid them unless you're sure the corner is safe.

Playing better against the computer

Don't grab as many discs as you can. It sounds wrong, but flipping lots of discs early often gives your opponent more choices and you fewer. Players who are strong at reversi tend to keep their disc count modest in the middle of the game.

Think about moves, not discs. A good position is one where you have plenty of safe moves and the computer has few. If the computer runs short of moves, it may be forced onto a square that gives you a corner.

Use the hover. Before placing a disc, hover over a few squares and see what each would flip. It's a quick way to compare options and spot the one that opens an edge for the computer.

Remember that passing is part of the game. If you leave the computer with no flipping move, it has to pass and you move again. Late in the game that can let you take several important squares in a row.

Count near the end. When the board is nearly full, it's worth working out which of your final moves flips the most, because the last few moves often decide the result.

Pausing and keeping score

Esc pauses the game, F1 explains the rules again and F11 makes the board fill the screen. Games by Zaweba keeps your plays, wins and best score on the game's tile, stored in a file on your own PC.

Other strategy games on the shelf

If you like Flip Discs, the Board games shelf has 13 other games against the computer. Drop Four is a race to line up four discs in an upright frame. Draughts and Mill are traditional strategy games on wooden boards, and Dots & Boxes is the pencil-and-paper classic where, a little like reversi, the moves you avoid matter as much as the ones you make.