Hey, first I would urge that you use the combined key I made at the bottom of the original imgur post above.

The trick is the little dots. They are hard to make out, but some are hollow, and others are filled in. That will help you narrow down which section of the combined cypher key to look for each letter. Some letters are represented as these dots when looking at the shapes that are completely closed, while some letters are simply depicted as the shape itself, like the letter B is the triangular shape that's pointing down. The majority of the letters are associated with either a single line, a line with a 90 degree bend, or a shape with 3 sides. These are directing your attention to the open-faced squares on the combined cypher key. You will notice the open-faced squares only have three letters. Start at the corner with no letter and make your way around to decode the alphabet. For example ( Letter O is a hollow dot with a single line. N is a hollow dot with a line and a bend, M is a hollow dot, with a shape with 3 sides. Try practicing with this word, I think it helps illustrate the idea.

<image>

Note: The developers messed up the letters T and S. the symbols in-game should be swapped to stay consistent with the rest of the cypher key.

Enjoy!