Chess has relatively simple rules (initial board layout, legal moves, win condition, some fanciness with en passant and castling, etc), but the game is endlessly complex, and there are more boards than a human being could ever see in his or her lifetime. Lisp is similar in that regard.
I'd say comparing it with Go might be easier, it has 8 rules, and can be played on a board of any size. I like to compare that to the 10 commandments in "The Little Schemer" or the 9 functions in μLithp.
