En Garde! (1975) is the first roleplaying game from Game Designers’ Workshop. It’s the earliest swashbuckling game (set in Musketeer-era France, or at least a simulacra of that era constructed from swashbuckling Hollywood films).

Like Boot Hill, this is primarily a one-on-one tactical combat game, though unlike Boot Hill, there is quite a bit going on beside the combat. The combat is about what you’d expect, though an interesting complication is that duelists lay out a series of pre-planned actions in secret and then attempt to reconcile them. There’s something neat about this programming.
More interesting is the focus on the character’s life that takes up the rest of the book. There is a mechanical social life that plays out week to week, with the character taking part in social activities and, hopefully, gaining status points. This system provides a loose narrative framework for potential tomfoolery, duels and other roleplaying opportunities. It’s the first social simulation I can think of and, the ONLY one, for several years. The next thing to emerge like this is probably Midkemia’s Cities simulator.
The other interesting thing is the game’s approach to military life — a necessary part of a gentleman’s life, taking up the entirety of the summer season with campaigning, which imparts special effects, benefits and, possibly, death. This is a clear forerunner to Traveller’s tours of duty lifepath system.
It also establishes a couple of GDW’s publication practices — the book is chapbook sized, give or take, and, aside of the Maurice Leloir illustration on the cover (from The Three Musketeers), there is no art inside.