Interesting idea about the Z4… I have a copy of Zuse’s book, and although we see that he was keen on the idea of programming for chess, it’s not clear to me that he ever wrote such a program or ran one on the Z4. (If he had, I expect he would have said so, as it would have been very impressive.)
Oh, I might move my vote to UTEC now… the Bertie person, Josef Kates (formerly Katz) helped design and build it and play games on it too, apparently:
Bertie the Brain was built to show off the potential of the little Additron tubes. “On the UTEC we were actually playing games, so I said, ‘Look, we can build a game playing machine’…. Practically everybody knows tic-tac-toe. I thought it would make a nice exhibit.”
See also here:
“It will be able to compute income taxes; to tell the trend of business at an electrified glance; to play a passable game of chess, and maybe even to forecast weather months in advance. Any of these operations will be done in less than a second.”
But we don’t know what games were played on UTEC, or whether chess ever was.