The game was set in a frontier region on the edge of civilization (the eponymous West Marches). There’s a convenient fortified town that marked the farthest outpost of civilization and law, but beyond that is sketchy wilderness. All the PCs are would-be adventurers based in this town. Adventuring is not a common or safe profession, so the player characters are the only ones interested in risking their lives in the wilderness in hopes of making a fortune (NPCs adventurers are few and far between). Between sorties into the wilds PCs rest up, trade info and plan their next foray in the cheery taproom of the Axe & Thistle.
The whole territory is (by necessity) very detailed. The landscape is broken up into a variety of regions (Frog Marshes, Cradle Wood, Pike Hollow, etc.) each with its own particular tone, ecology and hazards. There are dungeons, ruins, and caves all over the place, some big and many small. Some are known landmarks (everbody knows where the Sunken Fort is), some are rumored but their exact location is unknown (the Hall of Kings is said to be somewhere in Cradle Wood) and others are completely unknown and only discovered by exploring (search the spider-infested woods and you find the Spider Mound nest).
PCs get to explore anywhere they want, the only rule being that going back east is off-limits — there are no adventures in the civilized lands, just peaceful retirement.
The environment is dangerous. Very dangerous. That’s intentional, because as the great MUD Nexus teaches us, danger unites. PCs have to work together or they are going to get creamed. They also have to think and pick their battles — since they can go anywhere, there is nothing stopping them from strolling into areas that will wipe them out. If they just strap on their swords and charge everything they see they are going to be rolling up new characters. Players learn to observe their environment and adapt — when they find owlbear tracks in the woods they give the area a wide berth (at least until they gain a few levels). When they stumble into the lair of a terrifying hydra they retreat and round up a huge posse to hunt it down.
The PCs are weak but central: they are small fish in a dangerous world that they have to explore with caution, but because they are the only adventurers they never play second fiddle. Overshadowed by looming peaks and foreboding forests yes. Overshadowed by other characters, no.
Source