> As shatranj, new rules are introduced that cause the game to begin to resemble modern chess, including the rule that the King cannot be captured but must be rendered helpless: shah mat, the King is helpless, gives us the word checkmate.

Checkmate is by far the weirdest rule in chess, as capturing the king would lead to an essentially identical strategy and game, but without all the extra rule complexity of checks and checkmates.

(The exceptions are castling details and the stalemate rule. If kings could be captured, stalemates would not exist. But I argue that’s a feature not a bug. Stalemates do little to enhance fundamental strategy, their primarily use being hail mary gotchas for low level plays. In any case, kings-cannot-captured exists to make stalemates possible.)