How can an LLM play chess well?

Last week, I learned about https://parrotchess.com from a LinkedIn post. I played it, and drew a number of games (I'm a chess master who's played all their life, although I'm weaker now). Being a skeptic, I replicated the code from GitHub on my machine, and the result is the same (I was sure there was some sort of custom rule-checking logic, at the very least, but no).

I can't wrap my head around how it's working. Previous videos I've seen …

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