> TD Gammon, one of the very first algorithms to reach superhuman levels in a nontrivial game, learned by self play.

Thank you for mentioning this! Neural-nets self-trained bots have been a thing for quite a while in backgammon. Chronologically, from my memory: TD Gammon, Jellyfish, Snowie, GnuBG [1], XG (eXtreme Gammon) [2]

[1] http://gnubg.org/

[2] http://extremegammon.com/