The planning of units and buildings only took two days with the help of the Memory Playback Potion. But of course, Chen Mo had just the numbers, with no images for reference at all.
Chen Mo had previously posted a few concept arts of the World of Azeroth, including gryphons and hippogryphs, but most of the units still lacked artwork.
As Chen Mo had so many other things on his hands, he decided to hand over the buildings and units to Qian Kun.
Qian Kun built a system according to the attack/defence types of the different units and buildings to achieve a sort of balance between different races and units.
Su Jinyu on the other hand was creating artwork for a portion of the units based on her concept art, and the rest of it were outsourced to an art company.
As for the story, Chen Mo only left the story for The Frozen Throne to Zheng Hongxi, asking to make a draft for the story (including the plot and campaign), before revising it in the future.