Aion!

Join the twelve million players (and counting) currently adventuring in Azeroth as well as beyond the Dark Portal, and see what journeys await for those who would plumb the many secrets of this ancient realm. As a massively multiplayer online game, World of Warcraft enables thousands of players from across the globe to come together online - undertaking grand quests and heroic exploits in a land of fantastic adventure.

Zandronum is a multiplayer oriented port, based off Skulltag, for Doom and Doom II by id Software.

The game tells the story of a world destroyed by a conflict between robots and their human masters. Play as Tux in a quest to save the world from the murderous rebel bots who know no mercy. You get to choose which path you wish to follow, and freedom of choice is everywhere in the game.

Black Desert is an upcoming sandbox-oriented massively multiplayer online role-playing game by Korean video game developer Pearl Abyss. The game has been in development since 2010. F2P in Russia and Korea. P2P in Enlish, Francias and German language.

Daimonin is a community driven open source MMORPG.

Eternal Lands (EL) is a free, multiplayer, online role-playing game (MMORPG) created by Radu Privantu in 2002. The setting is a medieval fantasy world. There are historic elements such as medieval architecture and weaponry along with fictional elements such as other humanoid races and magic. It is made of up two main continents: Seridia and Irilion in the world of Draia. Seridia is the first continent, and the place in which new players spawn. It consists of 14 main maps, 7 storages, 2 main PK maps, and the only spot to find the Wraith. Irillion is directed towards experienced players. »

The Lord of the Rings Online (LOTRO) is the first MMORPG set in the world of J.R.R. Tolkien's The Lord of the Rings. LOTRO takes place in a persistent online world and is free-to-play

The Mana World (TMW) is a serious effort to create an innovative free and open source MMORPG. TMW uses 2D graphics and aims to create a large and diverse interactive world. It is licensed under the GPL, making sure this game can't ever run away from you.

Runescape is the most popular free MMO in the world, by Jagex Games Studio. Complete quests and win enormous treasures in a 3D world full of magic and monsters- all while never leaving your internet browser.