While our initial effort helped us determine the experience we wanted to provide, this second prototype really defined how we’d get there. Starting from a modern architecture—with all its security and stability changes—means the team’s efforts can be focused on pursuing an authentic classic experience. Any differences in behavior between our development builds and the patch 1.12 reference can be systematically cataloged and corrected, while still operating from a foundation that’s stable and secure.
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 or corruption problems, and generally are very imperfect recreations of the authentic World of Warcraft experience. As much as Blizzard has 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.
Blizz stated in a watercooler that they're using the 1.12 database as a starting point. I don't think it's a stretch for people to assume that most game features and mechanics will be in their 1.12 state. The kind of stuff I would expect to see reverted would be numerous AV changes, but I seriously doubt class mechanics are going to be reverted. I'd be surprised if the threat changes that ruin pre-naxx encounters are reverted.
15 Nov 7.3.5 client - worst pick to begin with So on your panel you explained why you couldn't use the old Classic Client and told us why u basically needed to recreate the entire game with 7.3.5. This was the worst and main wrong choice to begin with and I guess u guys noticed that but it was to late to go back. Instead of starting the Megaproject to recreate the entire old game you should just have outsourced your servers and build a new, small customer support team to work with the old interface there. By this pretty cheap demo and panel we now see which "insane idea" (quoting you) route you picked. That was a pretty bad pick and beside Sharding,16 debuff slots, new forced animations/sounds into classic graphics toggle, wrong stats, wrong mobaggro range, wrong UI, emptying the world by summoning stones, wrong npc pathing on quests and all the other crap this is by far the worst change to Classic. We take all this "its just a demo" as granted and trust you to fix those things until Release even if time runs low for the enormous amount of fixes needed there till summer 2019. Okay but 7.3.5 brings an endless list with its engine and code which is not comparable. Rogues won't be able to abuse front backstabbing skills, the physics are fundamentall different, there won't be no animation cancels, the movement feels like legion not classic, melees won't have the expanded range they often used to due code bug, Mobs do backpeddale when u "push" them, tldr blablabla. https://www.reddit.com/r/classicwow/comments/9ubyr6/wow_classic_demo_feedback_bugs_and_legion/ In short when people say "this doesn't feel like classic somehow" they're exactly right, because it is not classic. It is 7.3.5 with changed numbers and assets (BTW lots of your "classic graphic option" assets aren't even classic as well). The core of the new game ur building there is fundamentally different and you guys at blizz know exactly that it is, don't misslead anyone by sayin its "authetic" please. Basically it's like putting a Diablo2 character into Diablo3 and say "Here you go, this is Diablo 2". Guess what? No, its not.Uauu42 15 Nov
A different brand of challenge is presented by the PVP, which has undergone multiple phases and metas throughout the game's long lifespan. As in any competitive live game, some classes will be a fan favorite criticized as overpowered in one era only to be left behind in the next. The team says this is one of the main reasons it chose this specific iteration of WoW.

Hey kid… You want unlimited power? Buy now at the low-low-low-low-low price of your eternal soul ^(and the destruction of your entire planet, ruin of your culture and its way of life), but hey, don’t worry about that. Just think about those guys who called you names at Shaman school, think about the elders who cast you out, and think about the 15 foot tall burning infernal crushing their proportionally tiny skull between its… Do rocks have fingers? Who cares kid, just think of the power.
Most profitable professions are considered to be Herbalism and Enchanting in pair. You can have Enchanting only for Disenchanting skill, it will bring decent gold. Consider the fact of disenchanting all soulbound armor, not just selling them to a vendor, but I do not recommend to disenchant any kind of weapons, it is more profitable to sell it to a merchant if it is a soulbound item, or sell it on auction house if it is BoE (bind on equip).
That's not to say that everyone has an unrealistic vision of what vanilla WoW was like. There were already plenty of people on the WoW Classic forums pointing out that perceived bugs are just recreations of the original game. And as noted before, a flaw to one player is a key component of the original positive experience to another. WoW Classic will surely please plenty of purists in spades. But this goes to show that it won't be for everyone who has fond memories of the game circa 2006.