In Yonmoque players try to be the first to get exactly 4 of their pieces in a row. And no more than that... Get 5 in a row and you immediately lose the game!
Yonmoque applies the 'swapping mechanism' from Othello; opponent pieces that are trapped in between two of your own pieces are turned over so that they become your own. The differences with Othello are that you don't just place tiles on the board, you also move them around. Furthermore, placement and movement is determined by the colour of the squares of the board. There are squares in the colors of each of the players (white and blue), as well as 5 neutral squares. Given that there are less squares for the blue player (8 versus white's 12), the blue player always gets to play the first move.