Implement counter+speedrun AI: check if the second player is winning, if they are, then
counter and block; else look for lines which are closest to completion, rank them (by how
much is left to complete them, but perhaps other criteria to make it smarter like a move
which the player would be unable to counter), and then try completing the most eligible one
a more advanced ai could replace the else strategy with ahead prediction like chess AIs,
test all moves, rank each possible move with the best likelihood to win