If a line of two or more stones of the same colour become trapped by a newly-played and an existing stone of the other colour, they are removed.
First to make an ortho/diag 4-line (or more) wins.
Sample Game:
| j k l m n o p q r s t u v OO XX | . . . . . . . . . . . . . 0 ---------------- | . . . . . . . . . . . . . 1 -- p6 p5 q7 | . . . . . x . . . . . . . 2 o4 r6 s6 o7 | . . . . . . . . . . . . . 3 o6 r8 q6 n7 | . . . . . . . . . . . . . 4 o3 p7 p8 o5 | . . . . . x x o . . . . . 5 q5 p7 o2 q9 | . . . . . o . x o x . . . 6 o9 q8 resign | . . . . x x o : . . . . . 7 | . . . . . . : O o . . . . 8 | . . . . . O . x . . . . . 9 | . . . . . . . . . . . . . 10 | . . . . . . . . . . . . . 11 | . . . . . . . . . . . . . 12 | j k l m n o p q r s t u v