We spoke with two Blizzard developers who have been working on WoW Classic, and as they explained, recreating World of Warcraft 1.12 involved reintroducing bugs that have long since been patched out of the game. But even they have had to check their work against WoW’s long update history, since the time at which certain features were introduced or bugs removed has gotten a bit fuzzy.
A demo of the game was available at BlizzCon 2018, and was downloadable on home computers 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. Players started at level 15, and the only available zones were Westfall and the Barrens. It was based on patch 1.13.0, essentially patch 1.12.0 ported to a modern infrastructure. 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.