The files were discovered in December by Nick Roy, a Boston-based cyber-sleuth who regularly scans the North Korean internet as a hobby. Roy found a new North Korean website that outside visitors didn’t need a password to access, unlocking a trove of animation sketches, and shared them with the Stimson Center, a Washington-based think tank.

The documents include a series of Chinese instructions that have been translated into Korean. They call for making adjustments to the size and style of the animation. Among the documents, there is also an editing sheet written in English with specifications for animation work with “Invincible” printed atop.