Go is hard because there is a large branching factor and positional evaluation is hard.

Milestones:

• 1997: Janice Kim beats Handtalk in demo with 25stone handicap!
• 7 August 2008: MoGo running on an 800-node Belgian supercomputer cluster defeats US Champion Myungwan Kim with a 9-stone handicap. MoGo uses a stochastic search breakthrough.
• AlphaGo is a deep learning program that defeated the strongest human player in the world.
• Alpha Zero beat AlphaGo 100-0.