1. Start with whatever mid-size map (World stage I) surrounded with ocean. Land all new chars there (at the beginning of a world and anytime later). Limit the ores to bronze-age metals, small animals (like, no bears, moose, etc.), and a sub-set of biomes.
2. Time the stage I to 3-6 months. After that period enable another big chunk of map (e.g. going outside E and W). Use small ships like snekkja to explore new continent(s) and island(s).
3. The stage II world has all animals (big, small), all biomes, all bronze and iron ores as now through all 10 mine levels; also cheap precious metals. However, we cant make steel (because steel crucibles need a stone from the final stage III)
4. Time the stage II to 3-6 months. After that period enable the rest of the map. Use small/large ships to explore new continent(s) and island(s)
5. Finally steel is enabled by rocks found there. Could be even exposed on surface. Has all ores before and all precious metals and gems
6. Create a central primitive automated sub-quality trading center accessed via a portico, TH, or CS (aka Valhala market) where we could find random deals to buy/sell stuff. Item qualities random and below 75% of top qualities in the game. Items donated for quests go in here as well. This should allow all new characters to start up faster in later game but obviously at the expense of their efforts anyway.
as a results, all players in the same game
and world is changing keeping it more engaging, This just a generic view for the sake of discussion.