Gomoku
Gomoku, also called "Five in a Row", is an abstract strategy board game. It is traditionally played with Go pieces (black and white stones) on a Go board, using 15×15 of the 19×19 grid intersections. Because pieces are not moved or removed from the board, Gomoku may also be played as a paper-and-pencil game. The game is known in several countries under different names.
Go variants
Alak is a Go-like game restricted to a single spatial dimension.
Go can be extended to three dimensions. One example is Diamond Go, which uses the structure of a carbon diamond crystal lattice. With many such Go variants, the nature of the game changes dramatically the standard 4-connectivity of the points is changed, however, Diamond Go maintains this connectivity. Another example is Margo, by Cameron Browne, a variant played with marbles that can be stacked on top of one another.