World of Warcraft Classic restores the game to the state it was in patch 1.12.1 September 2006, before the launch of The Burning Crusade expansion. The level cap is set to 60, all expansion content is absent, and all the gameplay mechanics of the original version have been exactly replicated. As the game's multiple expansions have dramatically changed the gameplay since the launch version, Classic greatly differs from the modern version of the game.

Players can choose from the eight original races of World of Warcraft: humans, dwarves, gnomes and night elves for the Alliance, and orcs, trolls, tauren and the Forsaken for the Horde. The original nine classes are present: Druid, Hunter, Mage, Paladin, Priest, Rogue, Shaman, Warlock and Warrior. As in the original version of the game, only Alliance players can become Paladins, and only Horde players can become Shamans. Races and classes added in the expansions, such as Worgen or Death Knights, will not be available in the game. The game world is restored to its original, pre-Cataclysm state, and expansion areas such as Outland are not accessible.

To emulate the original game's patch release cycle, content in Classic will release in phases. This means that game content released in patches, such as the Blackwing Lair, The Temple of Ahn'Qiraj and Naxxramas raids, battlegrounds like Warsong Gulch and Alterac Valley, and certain items and quests will not be available until later. Unlike in the original game, these content patches will not modify the core game mechanics such as character abilities in any way, the game balance is set to the 1.12.1 version of the game.