Here is the full list of all 33 Bunker - there are The Underground Game achievements.
You have found the first secret!
You have found the secret number 2
You have found the secret number 3
You have found the secret number 4
You have found the secret number 5
You have found the secret number 6
You have found the secret number 7
You have found the secret number 8
You have found the secret number 9
You have found the secret number 10
You have found the secret number 11
You have found the secret number 12
You have found the secret number 13
You have found the secret number 14
You have found the secret number 15
You have found the secret number 16
You have found the secret number 17
You have found the secret number 18
You have found the secret number 19
You have found the secret number 20
You have found the secret number 21
You have found the secret number 22
You have found the secret number 23
You have found the secret number 24
You have found the secret number 25
You have found the secret number 26
You have found the secret number 27
You have found the secret number 28
You have found the secret number 29
You have found the secret number 30
You have found the secret number 31
You have found the secret number 32
You have found the secret number 33