Running alongside the main version of the game, Classic recreates World of Warcraft in the vanilla state it was in before the release of its first expansion, The Burning Crusade.

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.

[3][4] This means that game content originally released in patches, such as the Blackwing Lair, Ahn'Qiraj, and Naxxramas raids; battlegrounds like Warsong Gulch and Alterac Valley; and certain items and quests; became available after launch according to a six-phase schedule.

Every expansion has removed or replaced old content and introduced controversial or unwanted mechanics, resulting in many players expressing a preference for older versions of the game.

The second expansion, Wrath of the Lich King, removed the original versions of the Naxxramas and Onyxia raids and all items that could be obtained from them; added a Random Dungeon Finder tool, which many players felt spoiled the "social aspect" of the game; and made certain UI improvements that were criticized for reducing the need to read quest descriptions.

One of their oldest refusals was posted on February 21, 2008, by Drysc, who stated "We were at one time internally discussing the possibility fairly seriously, but the long term interest in continued play on them couldn't justify the extremely large amount of development and support resources it would take to implement and maintain them.

However, as expansions progressed and demand for legacy realms grew, private servers reversed focus and were seen as a way to faithfully re-create older versions of the game.

Private servers emphasizing fidelity to the official versions of the game were referred to as "Blizzlike" and included Feenix, Molten Core, Emerald Dream, Nostalrius, and Light's Hope.

The most popular was Nostalrius, which opened in February 2015 and had 800,000 registered accounts and 150,000 active players when it shut down in response to a cease and desist letter on April 10, 2016.

[7] In the wake of Nostalrius's shutdown, a Change.org petition for official Classic servers was created and received over 200,000 signatures, and ex-World of Warcraft team lead Mark Kern personally delivered it to Blizzard's president at the time, Michael Morhaime.

[8] Blizzard acknowledged the community's desires, and stated they had been discussing legacy servers internally for years but technical problems prevented them from implementing them.

[20] At the launch of the Wrath of the Lich King Classic, the developers announced a strategy of minimal changes seeking to reproduce the feeling of the game's original state as much as possible.

[21][22] This contrasts with the approach from Classic's launch in 2019, where Blizzard sought to preserve all the interactions and behaviors of World of Warcraft's original release, even ones that seemed irrelevant or unintended.

Blizzard opted to not include the Dungeon Finder, instead offering an improved in-game bulletin board system where players can look for groups for any type of content, in effort to promote social interaction.

[29] In the first content phase, the health and damage of all mobs in the Naxxramas raid were increased in order to provide players more of a challenge, due to the original release in 2008 being rather undertuned and quickly defeated.

With the introduction of the Ulduar raid, Blizzard implemented a series of changes and "catch-up mechanics" to make acquiring gear and items from Phase 1 easier and faster.

[38] For the Classic version, these recustomization options were made baseline, and any player could use in-game gold to completely recreate their character's appearance, including gender (now called Body Type).

[53] At BlizzCon 2023, Blizzard officially announced that Wrath of the Lich King Classic would continue into Cataclysm content, coming some time in the first half of 2024.

[57] The Rise of the Zandalari patch was introduced on July 30, 2024, adding reimagined versions of the Zul'Gurub and Zul'Aman raids as 5-player dungeons for max level characters.

[60][61] Blizzard also released Hardcore-only servers with the launch of the 20th Anniversary Edition, which feature previous permadeath mechanics and an optional "Self-Found Mode".

Players were able to pay to create copies of their existing characters on the Classic Era servers, which would stay in a 1.12.1 state, with all content phases unlocked.

[63] Reinvented versions of World of Warcraft Classic have launched as separate servers intended to give players a fresh experience with the game.

[66] On August 24, 2023, Blizzard launched official Hardcore Classic servers that feature permadeath and the ability for characters to "duel to the death", known as Mak'gora.

[64][67] This game mode was inspired by a community of players on Classic Era realms who used addons to create an unofficial permadeath experience, with other rules such as restricting access to the auction house or trading with other characters.

Persistent world events called Nightmare Incursions were also introduced, allowing players to complete specific quests and missions to gain reputation with a new faction and purchase rewards.

"[82] Polygon praised the difficulty of Classic and its overall design to nurture "social connections" in comparison to its modern counterpart, calling it a "faithful snapshot of a moment in time".