It seems like it’s partially based on LeanChess [1], which is 288 bytes long. I’d be curious to know whether this program was AI-assisted or written entirely from scratch, since Lean Chess was written at a time predating the era of LLMs.

Another thing that amuses me is that these tiny programs often claim to be “complete” chess engines while not actually implementing all the rules. This one doesn’t appear to support en passant, and likely doesn't have pawn promotion either.

If you’re allowed to arbitrarily redefine the scope of chess, then code size stops being as impressive a metric.

[1] - https://leanchess.github.io