Tried to make this post last night but my internet went out and deleted my progress >.<
I remember that in the early 2010s there was an MMO named Onverse. It was 3D and very of its time (2000s), with loads of y2k fashion.
It averaged about 100 players every day when I was playing, there were 'celebrities' (people who have been playing for a long time/spent a ton of money on the game), a gambling system, tools you could get to dig up currency or items with, pretty strange lore (something about aliens?) and loads of ways to clip out of bounds and go to the older versions of the hub world.
There were quite a lot of 'realms' in the game, ranging from holiday/event themed ones to really pretty worlds with houses you could buy and decorate in, and it had a pretty active roleplaying scene, too.
There were also events held by moderators that rewarded players' platforming skills with IGC. They were pretty fun!
Just making this post to see if anyone else remembers it! It was a big part of my childhood and seeing as its very 2000s I thought I'd bring it up here lol