Re: Grid Gauntlet
It's the numbers. Yes, chess has more pieces, but fewer - a lot lot lot fewer - options per turn.
Computers can play chess by exhaustively(ish, with tree-pruning) looking at all options. This doesn't work for Go.
E.g. first turn each in chess. White has 20 moves. Then black has 20 moves. 400 permutations.
First turn in chess. Black has 361 options (19*19); white has 360. 129,960 permutations.
Brute force won't work (q.v. the huge exponent vs. atomic in the universe, etc.) So either your evaluation and tree pruning has to be better, which is where the neural network stuff comes in.
[And for another poster, yes, parallelism exists but the search space for looking ahead is so vast it doesn't matter. 1,000,000 degree parallelism shaving 10^6 off of 10^170 isn't much of a dent.]