LLMs struggle at chess because it's not a language task. LLMs are trained to predict the next token in a text sequence not to optimize decisions over a structured game state. They embed patterns from chess notation, but they don’t maintain a real board state, enumerate legal moves, or propagate evaluations through a search. Interestingly, if you feed LLM the moves of a famous game like The Opera Game played by Paul Morphy, it may reproduce the continuation perfectly. Because that sequence…