grognard

An old soldier.

(games, slang) Someone who enjoys playing older war games or roleplaying games, or older versions of such games, when newer ones are available, and often complains frequently about newer games.

(military) A soldier or military enthusiast who pays meticulous attention to rules, details, and traditions, often respected for their expertise in areas that others might overlook.

(historical) A soldier of the original imperial guard that was created by Napoleon I in 1804 and that made the final French charge at Waterloo.