I saw a post on !games@sh.itjust.works with the video Death of a Game: The Sims Online by nerdSlayer Studios. It talks about how The Sims Online was received by fans and it's decline. Towards the end the video FreeSO is mentioned which is something I haven't thought about in years so I wanted to share it here.
FreeSO's GitHub page describes itself as the following:
A full reimplementation of The Sims Online, using Monogame. While FreeSO aims to be faithful to the original game, it includes many quality of life changes such as hardware rendering, custom dynamic lighting, hi-res output and >2 floor houses. If you simply wish to play, you can install FreeSO and the original TSO files using our installer on http://freeso.org, and it will connect to our official servers.
FreeSO currently depends on the original game files (objects, avatars, ui) to function, which are available for download from EA servers. FreeSO is simply a game engine, and does not contain any copyrighted material in and of itself.
It's a neat project I would recommend checking out. It can feel like a massive grind compared to The Sims though.
The Sims Online is also the basis for Project Dollhouse, FreeSims and Simitone. Three open source engine recreation projects.
All projects haven't had new releases in over three years as far as I am aware. I believe Simitone is the most stable of the three.
The Disaster Of The Sims 4 by Izzzyzzz talks about Project Olympus and how the Sims 4 was originally planned to be a multiplayer experience. I wanted to include this for those that want to go down the Sims online rabbit hole.
I think there are mutliplayer mods out there for The Sims 4 but I haven't tried them out myself.