you have to get the good or true ending to get the code. atleast thats what the thingy says when you read it.
if it's not there try google or the lucky/unlucky numbers that you get in the comedy section which wassssssssssss.... idk the order but 4,7,2,13 i think 7 and 2 being lucky numbers.
i have officially reached the ending and the code is 180112 i you're insisting on not playing the other endings though i will say playing the other endings is recommended for the code space
