https://scp-wiki.wikidot.com/scp-3125 contains a fun keypad to reverse engineer. I thought I could simply extract the password from the text but the author lightly obfuscated it (which makes more sense knowing that he has a programming background). I wonder what's the intended way of finding the code -- perhaps it's in one of the later stories.

edit: Oh, I saw it right after posting the comment. It's quite literally in front of your nose. Such a fun series.