Supporting older World of Warcraft legacy content in new patches and expansions is difficult according to Blizzard’s technical director on WoW, Patrick Dawson.

　　Since its original release 14 years ago, World of Warcraft has received numerous patches and seven expansions, adding new content and features to the existing game. While most changes affect end-game content, new additions might also influence older content that was already there, and according to Blizzard, considering all these factors is rather hard.

　　"World of Warcraft doesn't shy away from doing difficult things by any means," the technical director told Gamesindustry.biz in a recent interview. "It is difficult to support legacy content. Every time you release a patch or expansion you still have to make sure Ragnaros works, and Onyxia works, because there are people that still go back and do that. So the challenge is, how do you support legacy content while developing new content?”

　　Luckily for the team, insights have grown over the years and technology has evolved to help make things easier.

　　Making sure that Onyxia works in new patches and expansions might be harder than it seems"We've gotten a little smarter about things over the years. For example, there are features that are relegated to just one expansion now. The Artifact system for Legion is a good example of that. That's been sunset. We don't need to support that going forward. And what we've done is been able to take that and learn from it, figure out what's worked and what hasn't, so we can apply that to future expansions and not have to support other features like that going forward.

　　Dawson continued, “however, there are a ton of features we do have to support. One of the most important things from a tech end is we always look at modernizing wherever we can. When World of Warcraft shipped it was on single realms that were completely independent from all other realms. Now we're on a much more cloud-based infrastructure, which didn't exist in 2004 and is now the industry standard. We've modernized our game to make use of that, so we have a lot more resources we can share between different realms and a lot more connectivity we can provide to our players in their gameplay experience.”

　　"You can't expect any group of a few hundred people to hit every piece of content that's ever been developed over the past 15 years"

　　"We're constantly looking for ways to modernize so we don't have to have it be so painful to support legacy content."

　　The current-state of World of Warcraft and its infrastructure also effects Blizzard’s upcoming World of Warcraft vanilla server option, WoW Classic. As covered earlier, Blizzard recently confirmed that WoW Classic will run on patch 1.12 as foundation, and modern back-end improvements will likely be implemented in Classic.

　　Earlier, Blizzard’s Vice President and Production Director on World of Warcraft, J. Allen Brack, already said that vanilla's original graphics will be the starting point for WoW Classic.