A Campaign Framework
From the introduction:
Lords of the Nexus contains a Hexcrawl system built atop of 5th edition D&D. It allows the game to be run with minimal preparation and is heavily based on random chance, allowing the players and the GM to be equally as surprised by what events occur. There are rules mechanics for exploring a hex-based wilderness area, searching for and finding resources to build up a home base and above all, discovering portals to new exotic locations. This framework of additional rules is meant to fit any campaign setting and the example campaign outlined within also leaves a lot of blanks to be filled in, so it can easily be adapted to suit different settings.
Especially well suited for Hexcrawls in a multiplanar setting.