I had a lot of fun playing this, I think the game broke near the end though. Without warning I got a popup that said I had discovered the bunker and let me choose to stay or play endless mode. I chose the bunker, got the achievement, but the game text said something about the mutants evolving and needing to survive, and I was allowed to continue playing. I got the same pop up a few in game days later, and another time after that. Nothing about the game play changed, the enemies still say [pre glow] and I'm almost certain I hadn't finished finding the bunker (the last in game text I had said the bunker signal was weak or something).