"West Marches is a sandbox style of D&D campaign, created by Ben Robbins and popularized by Matt Colville, designed to facilitate player agency and reduce ‘mindless plot following’ by putting a large group of players (10+) in charge of where they go, what they do, and when they play."
The original experiment:
http://arsludi.lamemage.com/index.php/78/grand-experiments-west-marches/
A video explaining how it can work:
A write-up on improving the game:
https://www.reddit.com/r/DMAcademy/comments/adn178/
My intent with this game is to facilitate a sandbox game with a large player base that can feature exploration of a mega-dungeon, discovery of exciting locations, daring forays into the wilds, factionalism and development and taming of the harsh wilds. Players forming their own guilds, or joining pre-made ones. Building strongholds and settling. Or simply knocking over wild beasts and evil things.
While Brickmane, the safe and comfortable home of Runesbane, won't be the star of any adventures as Robbins suggests, I do hope to include it and the factions that live there as things that provide incentives to explore the wilds.