In 1989, Victor Allis "solved" the game of Connect 4, proving (apparently) that the first player can always force a win, even if both sides play perfectly.

In 1996, Giuliano Bertoletti implemented Victor Allis's strategy in a program named Velena:

http://www.ce.unipr.it/~gbe/velena.html

It's written in C. If someone can get it to compile on a modern system, it would be interesting to see how well the AlphaZero approach fares against a supposedly perfect AI.