I have an idea for a time based event. In most survival games, for example, project zomboid, nature starts to retake civilization after the collapse. Buildings turn to rubble, grass grows, roads crack. What if something similar happens in the narrative where the blue mold you encounter in the bunker starts to overtake some parts of the world. It can build tension, though I can see how it can become a tedious thing to deal with, especially if you struggle with maintaining your needs.
I was thinking this event would happen late into the game where (depending on luck) you’ll have plenty of Zanthrozia, elastinups, etc to keep you going. How does day 100 sound?