World of Warcraft: Classic

World of Warcraft: Classic (later rebranded Classic Era) is a recreation of "vanilla WoW" as a server option for World of Warcraft announced at BlizzCon 2017. The goal of Classic is to let players experience World of Warcraft as close as possible to what it was before The Burning Crusade.

With the addition of World of Warcraft: Burning Crusade Classic, existing characters must choose whether to stay in Classic or move on to the expansion. A character can be activated for use in both versions via the Activate Clone service, which creates a copy of the character as they were when the expansion choice was made.

Development
Before work began on World of Warcraft: Classic, it was only possible for players to experience the original World of Warcraft by using private servers, which are illegal, often have stability problems, and are generally imperfect recreations of the authentic World of Warcraft experience. As much as Blizzard had been aware of the desires of their community, until recently it seemed impossible for them to emulate Classic servers due to the technical hurdles of essentially having to run two massively multiplayer online games side-by-side. A breakthrough was then achieved that made it possible to run Classic servers on the modern architecture of current World of Warcraft servers.

Blizzard had begun conceptualizing Classic by early 2017.

Even though a modern server architecture is used, Classic servers won't have the same features that current World of Warcraft does. There won't be cross-realm servers or Looking For Raid and Dungeon Finder automatic party matchmaking. There are still a lot of questions about how the team will tackle it. This endeavor is being undertaken by an entirely separate team at Blizzard from the one working on World of Warcraft and its next expansion.

In June 2018, the team settled on using patch 1.12 as a foundation for Classic. They managed to have a locally rebuilt version of patch 1.12 running internally, using modern code and data architecture.

A demo of the game was available at BlizzCon 2018, and was downloadable on home computers (64-bit client only) for anyone who purchased a BlizzCon ticket or virtual ticket. The servers became available when Opening Ceremony started at BlizzCon 2018 and was set to end on November 8, but was extended until November 12. Player levels ranged from 15 to 19, and the only available zones were Westfall and the Barrens without access to dungeons such as Deadmines and Wailing Caverns. It was based on patch 1.12.0, ported to a modern infrastructure as patch 1.13.0. The first day of the demo, there was a playtime limit of a cumulative 60 minutes with a cooldown of 90 minutes, applied through the BlizzCon Exhaustion debuff. The debuff was removed on the second day of BlizzCon 2018.

Release
Classic launched globally on 27 August, 2019 at midnight in Central European Summer Time, following an early-access period when players could download the client and create toons (to reserve the name) but not play them. High volumes were partly mitigated by larger server sizes than the original, and Blizzard introduced temporary layering technology that was similar to sharding but not cross realm. Nevertheless, some servers experienced extreme login queues forcing the rapid creation of additional servers in all regions.

In order to reproduce the original Classic experience, content was added via multiple stages mimicking selected major content patches back in the day:
 * Phase 1 (Classic Launch): Molten Core, Onyxia, Maraudon
 * Phase 2 (released November 12th, 2019): Dire Maul, Azuregos, Kazzak, Honor system (including dishonorable kills), PvP Rank Rewards
 * Phase 3 (released February 12th, 2020): Blackwing Lair, Darkmoon Faire, Darkmoon deck drops begin, Alterac Valley, Warsong Gulch
 * Phase 4 (released March 10th, 2020): Zul'Gurub, Green Dragons, Arathi Basin
 * Phase 5 (released July 7, 2020): Ahn'Qiraj War Effort begins, Ahn'Qiraj raids (Ruins and Temple of Ahn'Qiraj) open when the war effort dictates, Dungeon loot reconfiguration: Tier 0.5 Dungeon gear, Relics, drop rates and location changes
 * Phase 6 (released December 1, 2020): Naxxramas, Scourge Invasion, World PvP objectives in Silithus and Eastern Plaguelands

Additionally, some content such as updated Blackrock Depths loot, Sunken Temple class quests, high-end Timbermaw Hold, Thorium Brotherhood and Argent Dawn reputation rewards came later than Phase 1. Finally, the temporary layering at launch was to be discontinued or replaced no later than the release of world bosses with Phase 2.

Following the successful launch, Blizzard CEO J. Allen Brack teased his own earlier statements that Classic would be a bad idea by recalling an ice cream metaphor:

NoChanges controversy
During development until launch, many players disagreed quite vocally on Blizzard's forums and social media about the direction Blizzard should take with World of Warcraft: Classic. #NoChanges became a popular slogan for the assertion Blizzard should reproduce as authentic a Vanilla experience as possible. Critics argued Blizzard should apply 15 years of hindsight to consider limited changes.

Gameplay
#NoChanges proponents asserted gameplay should remain as authentic as possible, contrasting any suggestions for balance tuning or using modern technology to remove former limitations. For example, Classic could have removed the former limit on buffs and debuffs or given protection paladins a taunt ability to substantively improve their raid-tanking viability.

In general, Blizzard developed Classic without any such changes. Not only were classes and combat mechanics largely retained from Vanilla, but Blizzard deliberately introduced 400ms spell batching (until patch 1.13.7) to simulate technical limitations that modern architectures could have avoided completely.

AddOns
#NoChanges were often cited by both proponents and critics of including AddOns in Classic. Arguments against including AddOns asserted that they took away the authenticity of the Vanilla UI or altered the community's behavior (ie, becoming "mandatory" for high-end performance because peers would use them and deny the right for others to join without using them also). Conversely, arguments in favor of AddOns asserted that they were very much part of Vanilla. Indeed, addons introduced many features that were later absorbed into the native UI.

This dispute also extended to how the API was modified to fit Classic. Blizzard removed functions that did not exist in Classic, but this actually reduced some capability versus what was possible in Vanilla. This reduction was because the API evolved in patch 2.0.1 to prevent automation and improve security, but these changes were accompanied by new functions so AddOns could reproduce their Vanilla capabilities within acceptable boundaries. Classic did not keep all of these new functions; for example, the focus frame and corresponding  command were removed despite AddOns introducing this feature in Vanilla. In patch 1.13.3, Blizzard further modified the API to remove some convenience functions that were entirely possible to duplicate using longer, more inefficient code snippets. However, some of these were restored in patch 1.13.4 suggesting tacit acknowledgment that API trimming had gone too far.

Notes and trivia

 * The original idea was to have the content unlock in 4 phases. This was increased to 6 phases in March 2019.
 * The Burning Crusade and Wrath of the Lich King classic servers are not out of the question, depending on the success of the original launch.
 * The Classic beta started on May 15, 2019, with the level cap limited to 30. The level cap was later raised to 40. The Classic beta ended on July 12, 2019.
 * World of Warcraft: Classic won the 2019 Golden Joystick Award for "PC Game of the Year".
 * When choosing to keep a character in Classic instead of moving on to, Nefarian's voice plays, saying "Let the games begin!"