Reversi

The board starts with four discs in the centre — two black, two white, in an X pattern. Black moves first. To make a legal move, place your disc on an empty cell so that one or more of your opponent's discs are bracketed between your new disc and another of your existing discs along a straight horizontal, vertical or diagonal line. All bracketed opponent discs then flip to your colour.

If you have no legal move, your turn is automatically passed. The game ends when neither player can move — typically when the board is full. The player with the most discs of their colour wins.

AI · Easy grabs corners when it can and plays randomly otherwise. AI · Hard uses a 3-ply minimax search with a positional weight table and mobility heuristic.