Being made in Unity:
This is not like Deep Blue playing chess. A skilled player could easily outmatch the autoplay. All it does is scan the board against a long list of patterns and when it finds a matching pattern, makes the appropriate move.
The purpose is to determine par scores for various randomly-generated levels.
Done in Unity 2019.
Patterns were made by hand. All the “next move makes a 3 in a row” are checked, followed by a modest sampling of “next move will be one move away from 3 in a row”. That’s it, only looks ahead by 2.