The playing field consists of arbitrary arranged squares.
The players make one after another a horizontal or vertical line on a squares.
When you make the last line of a square, you get a point, your icon is drawn inside the
square and you have to take another turn. The border of the playing field is considered to
be marked.
If all sides of all squares are marked the game is over. The winner is of course
the one who occupied the most squares.
