After buying the game, players pay a monthly fee to play online.
With The Sims and its numerious expansion packs being the best selling computer game of all time, many experts predicted that TSO would become the most popular massively multiplayer game. As of early 2004 this is not the case; TSO has seen only a fraction of the subscription numbers aimed for by the game's publisher, Electronic Arts.
Technically notable is that the Maxis servers behind The Sims Online run the open source software JBoss.