As far as I know, MMO creators gave up and used static instances, which degrades most MMOs to multiple regular/non-massive multiplayer games stitched together.
Sadly true. There have been games with large, seamless, 3D worlds combined with multiplayer for a long time (late 90s at latest), but almost all new games use some combination zones (e.g. shared spaces, but broken up), or instances (spaces shared only with a small group), or phasing (spaces shared only when you're in a similar game state), or the Destiny-style "we'll have people show up whenever we feel like it" tech. That last one seems hugely popular these days, to the point it's showing up from the other direction -- other people showing up in your single player game.
I think it's because of a combination of technical difficulty and game design reasons dealing with overcrowding and camping and other bad behavior.
And I also think it's a total cop out and decimates any sense of "place" in these games, which I think is so important in games like these.
If anyone has examples of modern games that don't do most of these these things, I'd love to hear it. I'm not up on all of em, particularly the ones in the primarily Asian market.
Me too wondering if there are any games could have done it without phasing or any doing the equivalent.
It seems to be impossible to handle unlimited players that are crowded together, even despite all the design issues. Because the logic and synchronization could grow in superlinear complexities in those scenarios. Clustered states and dynamic instance provisioning could ease some degrees but that actually can only solve sublinear to linear complexity problems at most.
With that being said, I played the Elder Scrolls Online many years ago. There were definitely phasing mechanisms. But when it just came out, there were like one thousand users PVP in Cyrodiil. Compared to World of Warcraft which one hundred players AOE in a city could make the server crawling it's already pretty impressive to me. Not sure how they have done it.
EVE Online is still primarily one single shared environment, as far as I'm aware. They added instances for some content back in 2018 (from a quick Googling), but otherwise it's not sharded in any way, to my knowledge.
Eve has some advantages that let it avoid some problems. Space is split up into distinct solar systems with a "jump" required to transition from one to another, so a system can be controlled by a single process.
Within a system, your area of interest is always the grid you are in, which is equal for all players in that grid. "Grid" despite the name is a dynamic boundary that contains all nearby players that are likely to interact with each other. The game doesn't allow most cross-grid interactions, probably to make implementation much easier. I think they get away with this since solar systems are so large and you have to be relatively close to interact with anything.
Some of these designs became problematic.
Players can perform "grid-hacking" where they manipulate the shape and position of these grids so that they can suddenly cross a grid boundary to ambush or escape other players.
I haven't played in a while, so some of this might work differently now. The lack of server scalability within a system also causes time dilation, which besides making fights slower and boring also gives more people enough time to join and rejoin fights and cause more time dilation.
