The Goal of the Game. The winner is the player who has more discs of his colour than his opponent at the end of the game.
Starting Position. At the beginning of the game, four discs (two of one player and two of another) are placed in the centre 2x2 square of the board.
Making a Move. At his turn, a player must place a disc of his colour on one of the empty squares of the board, adjacent to an opponent's disc. In addition, by placing his disc, he must flank one or several of his opponent's discs between the disc played and another disc of his own colour already on the board. He then flips to his colour all the discs which were flanked. The discs are neither removed from the board nor moved from one square to another. If, at your turn, you may not make a move to flip at least one opponent's disc according to these rules, you must pass your turn and it's once again your opponent's turn to play. But if a move is possible, you must play it.
End of the Game. The game is over when neither of the two players has a legal move. Generally, this happens when all squares of board are occupied. However, it is possible that some empty squares will remain where neither player may move.
Blackhole Reversi. This game has the following changes from the classic Reversi rules: one square is randomly chosen at the beginning of the game to be a Blackhole, Neither player may place a disc in the Blackhole, the Blackhole cannot be used in flips.