PlaneShift is a cross-platform fantasy MMORPG in development. Client software is available for Linux, Windows and Mac OS X. It is a no-budget project produced by a group of developers, founded by Luca Pancallo, and guided by the Atomic Blue non-profit organization. The server side engine code is completely written from scratch by the PlaneShift team, while the 3D rendering features are based on the Crystal Space 3D engine. The game engine is released under the GPL. The content is released under a proprietary license. The game is free to play, with no monthly fee, no premium upgrades, and no advertising on the site or in game. The game is currently in the alpha stage of development, at version 0.4, codenamed Steel Blue. The first version released February 10, 2002, 0.1, was codenamed Atomic Blue and the next version, 0.2, was codenamed Molecular Blue. The Molecular Blue server was shut down on December 16, 2004 and replaced with 0.3, Crystal Blue. The current version, Steel Blue, was released to the public on March 2, 2008.

PlaneShift is set inside a colossal stalactite named Yliakum, divided into eight levels, of which the lower two are flooded. Life is possible because a huge crystal, named The Azure Sun, draws light from the surface of the planet. PlaneShift currently has 12 playable races that all have their own homelands and characteristics[7]. Outside of Yliakum are the Stone Labyrinths and through these the player can access even more areas, like the cave in which the stalactite hangs. In Steel Blue, the cities of Hydlaa, Gugrontid, part of Ojaveda and the Bronze Doors Fortress can be accessed. The other levels of Yliakum and the cave it hangs in are not yet accessible.

One of the main concerns of the PlaneShift staff is roleplay. This is accomplished by extensive attention to roleplay details, background stories, books, and quests. New players are encouraged to read the guide set forth by the staff which details how to properly act in character. In the world of Yliakum are GMs who help the players stay in character, along with players who spend a lot of time to develop the persona of the characters with which they play.

PlaneShift features an expansive character creation tool containing two options. The first option is to choose to make a "quick" character, in which you choose a skill path and a character is randomly generated for you. Alternatively you can choose to make a character from scratch. Starting from scratch allows you to choose every aspect of your character from childhood, life events, parents, race, name, and appearance. Only after choosing all of these options are your character`s stats revealed.

Yliakum is populated by many creatures that can be fought for loot and experience, ranging from simple rats up to large creatures which may require many players to defeat. Players may also engage in duels on a voluntary basis, which requires both parties to agree to the conditions of the duel. Players may fight with bare fists, known as melee, or wield a variety of swords, axes, daggers, and hammers.