One of the most difficult challenges to overcome for Wrath of the Lich King Classic comes from its coding. Consolidating all the information of Classic WOTLK Classic Gold, Wrath of the Lich King and the retailers World of Warcraft into a one-of-a-kind experience is an arduous process. According to Birmingham they require importing the code from Vanilla World of Warcraft, Burning Crusade, and Wrath of the Lich King and aligning it with the previous and present Classic or retail World of Warcraft versions.

"We're dealing with six different version formats and trying to ensure that the modifications that occur in one format are properly reflected in the correct place when we release the next version in the future. It's a challenge that we are grappling with by documenting the changes , and then looking at which versions make an ideal sense to use."

According to Birmingham Birmingham, inside-game World of Warcraft maps are among the most challenging parts to convert. "[The World Map] system changed significantly throughout the various patches" Birmingham explained "We constructed all the systems, and later refactored them in order to make them more cohesive." The data that comes from the maps from various eras from World of Warcraft are all different and streamlining them was a surprise challenge.

Also, spells have been formatted , reformed and formatted many times in the past as well as, ironically, Zierhut was the one to do most of the spell script formatting for the retail version of World of Warcraft in the past. "And we'll need do it all over again!" he lamented.

"Now, it's time to fix"the Lich King version that never got corrected." Wrath of the Lich King was the first instance of abilities having unique spell scripts that could be attached to different difficulties of spells buy WOTLK Classic Gold, however, the growing complexity of the Warcraft code meant they needed change to function within its engine.