Each door has a matching magic key hidden somewhere inside the bunker. These keys are huge, just carrying one of them would exhaust anybody. What makes them "magic" you ask? Well, they teleport to a random location inside the bunker if they're put down. Make sure you crouch down and catch your breath every once in a while or you'll exhaust yourself. If you get exhausted, just make sure you rest for a while and you'll be running again in no time. Your lamp has very limited energy supply so use it wisely, once it's gone it's gone for good. Oh, and watch out for Boofie. Why am I telling you all this? I'm not! It's all in your head, you're crazy. Now go get some keys, crazypants.