this giant vault is the in the final room of the game before a secquence to get back to the start of where you came from. aka the exit. when you start the game the gate suddenly closes on the door and locks shut. this safe has many things you need to do in the final room to open it. whats inside? the config to open the gate. after you open the gate a escape sequence activates. and you have to run while entitys are chasing you and you have to hide.
c2a
