Answer: Go

The ancient Chinese game of Go, played with black and white stones on a grid ranging in size from 9×9 to 21×21, is truly a game of possibilities. While other games, such as Checkers, will always result in a stalemate when played between a highly proficient machine and a highly proficient player, due to the limited number of moves and stable end-game, this is not the case with Go.

When played on a 19×19 grid board, the most common play size, there is the potential for 2.08168199382×10^170 legal moves. While most Go games only last for 200-400 moves, it’s possible for a game on that size board to play on for a Quindecillion number of piece movements (10^48 moves). The amount of computational power necessary to predict future movements is extremely prohibitive and only the most powerful super computers available even remotely stand a chance against the highest ranking Go players.

To put this in perspective, the very best computer chess players are able to beat the very best human players. The very best computer Go players are able to achieve the proficiency of a competent but low-ranking professional player. The best Go playing programs are only able to consistently win on smaller 9×9 boards–boards traditionally reserved for younger and amateur players to learn the basics on.