TriGo

TriGo is implemented at iggamecenter. Its full rules are described here.

Essentially, it is go played on a triangular lattice within a hexagon. Each move consists of playing two stones (except for the first move of the game, where only one stone is played).

Strategy

One difference to Go is that, since one is allowed to place two stones in one turn, it is necessary for groups to have three eyes to be alive.