@aran more recently, i got asked for some assistance with an FDS adventure game called Dead Zone
the game's final puzzle is a doozy; it involves figuring out that the (wrong) passcode you've been given is an alphanumeric cipher for one word, and determining that the RIGHT passcode is a different word encoded into an alphanumeric cipher (mercifully, despite the game being in Japanese, the cipher and both words are in English!)
@aran there is an element of abstract thought this puzzle demands that i don't think the game clues quite well enough; it hints that there is some connection between the two passcodes and the antagonist's thoughts/motivations, but not to the alphanumeric cipher
i don't know what the finished translation patch goes with but i do remember offering some suggestions hinting a bit more explicitly at the passcode being a cipher