- S4 League
- Saga
- Saga of Ryzom
- Samurai of Legend
- Savage 2
- Savage Eden: The Battle For Laghaim
- Scions of Fate
- Scions of Fate (Yulgang)
- Seafight
- Seal Online
- Second Life
- Secondhand Lands
- Secret of Solstice SOS
- Secret of the Solstice
- Secrets of Mirage
- Secrets of War
- Settlers : Rise of an Empire
- Shadow of Legend
- Shadow Ops
- Shadow Worlds
- Shadowbane
- Shadowhunter Bloodlust
- Shadowmere
- Shadowtale
- Shaiya
- Shattered Galaxy
- Sherwood Dungeon
- Sho Online
- Shot Online
- SilkRoad
- SkipperMania
- SmallWorlds
- Smash Online Europe
- Soccer Manager
- SocioTown
- Solar Empire Infinium
- Soldat
- Soldier Front
- Space Conquer
- Space Invasion
- Spine World
- Splash Fighters
- Star Sonata
- Star Wars Combine
- Star Wars Galaxies
- Star Wars: The Old Republic
- Stardoll
- Stargate Worlds
- Starport Galactic Empires
- Starquest Online
- Stellar Frontier
- Stick Arena
- StoneAge 2
- Street Racers
- Subspace Continuum
- Sugar Rush
- Super Shift
- Superstar Racing
- Supremacy 1914
- Survival Project
- Sword of the New World
- Syrnia
List Of Multiplayer Online games 123 S (Text)