I entered and exited the bunker, but I DID NOT GET AN ACHIEVEMENT! I also couldn't find the gas mask, even though I had all 4 types of keys with me, and some doors don't open for any keys at all and are just permanently locked! I found the door that lead back to the start of the level, but no text appeared and I was greeted by Mr. Cleany! I exited the level, checked my achievement list, and what do you know? A BROKEN ACHIEVEMENT!