Spatial OS was supposed to revolutionize big-world MMOs. Huge numbers of players in the same world. Lots of hype in 2017-2018. Improbable claims to have raised US$500 million to build it.
Then, not much. Worlds Adrift and Mavericks went live and then went broke. Sominium Space has user counts in 1 digit. Nostos is supposed to come out this month, but it's apparently heavily sharded, with only a few players in each instance.
What went wrong? Doesn't work? Too slow? Costs too much? Doesn't scale? Having to run on Google servers is unacceptable?
Any big-world technologies …