Just finished it. So you're not supposed to get all the codes?
Hello - thanks for playing!
It's not required that you find all the codes before reaching the final scene. I did this because I wanted to be able to add some very difficult codes without worrying that it would be something that blocked people. If you'd like, the following site has some hints for any of the codes you are missing:
http://yamguy.webflow.io/twilightwarhints
Also, this game was created as a companion to a TRRPG which also has some codes hidden in the physical book. However, those are a separate set of codes that only unlock some audio clips in the game - they are not required.