File data: This is often very dense data like 3D models, textures, animations and terrain. Our user interface is built up from XML and Lua files. Many of the art files do not use the same file formats that commercial art tools spit out. Our build pipeline takes these raw art files and translates them into something optimized for our game to read and process.

 ":"  -  Any time a step ends in a ":" instead of a "." means that the next step is part of the current step you are on.  This generally means the next step should be done while working on the current step.  This means every "start working on" or "continue working on" will end in a ":".  But this is used with other occasions as well, so keep this in mind. 

So we asked ourselves, would it still be possible to deliver an authentic classic experience if we took our modern code, with all its back-end improvements and changes, and used it to process the Patch 1.12 game data? While that might seem counterintuitive, this would inherently include classic systems like skill ranks, old quests and terrain, talents, and so on, while later features like Transmog and Achievements would effectively not exist because they were entirely absent from the data. After weeks of R&D, experimentation, and prototyping, we were confident we could deliver the classic WoW content and gameplay without sacrificing the literally millions of hours put in to back-end development over the past 13 years.
Fortunately, WoW’s modern editor is able to perform some of these data conversions, and for the terrain data we could convert it with the same editor we used on Battle for Azeroth. The modern editor “knows” how to load the old terrain format and how to transform it into the new terrain format and export it to the modern engine. This corrected the issues of campfire placements and the appearance of trees, among other things.
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.[4] Players started at level 15, and the only available zones were Westfall and the Barrens.[5] 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.[6] The debuff was removed on the second day of BlizzCon 2018.[7]