Right now, there's a huge boom in "blockchain metaverses". Search for "metaverse" in News for info. The idea is to have a virtual world in which you can buy scarce land and maybe scarce objects. There are at least a dozen of these things. As virtual worlds, they're awful. The graphics are bad, the worlds are tiny, you can't do much, and nobody goes there. It's all about selling land and "rares". There are at least two such things where they skipped building the virtual world and just sell land on a map. On top of this fluff, there's now a virtual land real estate investment trust.
I want to see a good big "metaverse". Right now, 19 year old Second Life is still the best recreational virtual world, despite a lack of forward progress in the last few years from Linden Lab. Roblox is getting steadily better, moving past their blocky origins. IMVU is trying harder. Epic keeps talking up the "metaverse", but all they have shown so far is a level editor for Fortnite.
Improbable [1] raised US$400 million to build a back-end system for really big virtual worlds. It even works, more or less. But you have to host on their servers (Google's, actually) and the thing is so expensive to run that the three indy games that used it all went broke. Since they raised too much money, they now have two in-house game studios, which have shipped nothing.