I recently started on a new series where I take the Survival Game project (open-source on GitHub) which you might remember from some years ago and upgrade it to work with SpatialOS. In case you don’t know, SpatialOS is a hosting platform for multiplayer games and can scale up to MMO-scale hosting which is pretty interesting!
Single world shard, milions of entities, thousands of players. What defines the density of replication is range and not fixed tiled zones. For a single location that runs too many players it would create multiple authoratitive dedicated servers under the hood… sort players between those servers, and update players replicated info and transforms between each other. So imagine a crowded city - each server can handle 100 people (for example) and if 400 people gather at single location there would be 4 servers updating each other, and each of them updating 100 players. So each player see all 400, though update rate of some would be better then others as they would be sharing server, while others just update.
best part is - you dont see it happen. no loading, no instancing. You can have single unite world. Or you can have normal session based servers still with layered dedicated servers underneath.
It allows to for example run ten of thousands of ai, and sets of thousands of physx objects at once. in multiplayer. You could also do some study simulation on massive scale.
It’s pretty sweet