Blizzard has revealed more details of the World of Warcraft classic edition. It will combine the 2006 state of the game with 2018 technology.

The idea is to blend nostalgia for the classic version of the game (before the first Burning Crusade expansion) with the benefits of modern editions, including measures to prevent cheating

The company has detailed the process and challenges of making the game, announced last November, in a blog post. It’s settled on working from Patch 1.12 of the original game, better known as Drums of War. That’s because this is “the most complete version of the classic experience.”

Originally the developers tried the approach of literally taking the original source code and trying to update it to the modern set-up. As well as the predictable crashes and video card compatibility problems, it proved too difficult to make it work with the security and login systems used for today’s WoW servers.

Instead they took what they considered a counterintuitive approach: taking the current codebase and trying to get it to process the 2006 game data. That didn’t prove simple as it involved a lot of conversion. For example, the data layout format used today is much more efficient, particularly when it comes to empty fields.

One example given was that some spells have multiple effects while others only have one. In the original table format, every spell had three spaces to list effects, meaning many entries simply read ‘nothing’. In the modern format, there are more tables but each is much more efficiently organized.

The developers say that while the conversion isn’t a simple task, the approach means “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.”