Anarchy Online – the first ever science fiction MMO – is now on Steam! Compete and cooperate with thousands of player simultaneously on a vast, alien world. Join humanity nearly 30,000 years in the future in a world of perpetual conflict and scientific marvel.
Steambirds Alliance is a massively-cooperative bullet-hell shooter! Fly with dozens of your feathered friends in an open world full of cruel cat bosses and endless waves of deadly bullets.
Screeps: World is an open source MMO RTS sandbox game for programming enthusiasts, wherein the core mechanic is programming your units AI. You control your colony by writing JavaScript which operates 24/7 in the single persistent open world filled by other players on par with you.
Mass Exodus is a 2D/3D RPG MMO point-and-click. In Diaspora Mass Exodus you will take control of one of many types and classes of ships and make your way out into one of multiple solar systems within a large and expanding galaxy. Here you will carve out your destiny and make a name for yourself among the stars!
Aberoth is a fantasy massively multiplayer online role playing game with charming retro graphics and tons of freedom.
Perpetuum is a persistent, sandbox, single server, massively multiplayer sci-fi rpg (MMORPG). Control huge robots and mechs to gain access to an alien planet’s resources and knowledge, amass huge wealth, or even claim part of the world for yourself using terraforming and complex infrastructure.
Your blocks, your castle, your world! Build anything you can dream up and explore with other players! Cubic Castles is a mini-MMO that combines the best of block-building and 3D platform action! Create fantastic parkour challenges, explore worlds made by other players, or even make friend!
The Void King is raising an army in secret. Death has chosen you as his champion to bring him down. Adventure & quest alongside your friends in this bizarre cross-platform MMORPG from the creators of the original, and comically-redundantly named… AdventureQuest! Did we mention the darn-near-weekly free DLC?
CSC is a casual space MMO with fast-paced combat, a robust player economy, and an uncapped crafting system. CSC is a game in active development.
Atulos Online is a free to play 2D medieval MMORPG. You can choose from many different characters including Mage, Knight, Dwarf and Guardian. The story unfolds as a confrontation with the sorcerer Atulos draws ever closer.