Go, the only (?) traditional game in which computers can't beat human opponents! Even a medium-level human player can beat a very sophisticated computer program easily, unlike with chess. The reason is that Go creates a huge number of possible moves. With chess, there's only a few dozen (?) moves available at first, and then the number goes down quickly; while in Go, on a large board, there's 64 possible moves; next turn gives you 63 moves, and so forth.
The rules are that a pebble is placed on intersection, four lines coming out of it are the pebble's 'lives'. If all lives are taken by enemy pebbles, that pebble dies, if a pebble is in a group, it's kept alive by lives available to any other pebble in a group. Pebble cannot be placed in a spot where it'd die - therefore a group can be protected by having an 'eye', or a space enclosed by the group which gives it lives that can't be taken away.
Except that if there is only one 'eye', it can be killed by placing an enemy pebble in it, because it kills the whole group right away and by doing so keeps alive.
If the group has two 'eyes', it's 100% safe, even if it's completely surrounded.
A pebble can be placed anywhere on the board except for spots where it'd have no lives.
Go is harder than it looks.