There is an ongoing threat near the base. Maybe your base is built on top of a slumbering Silurian colony. Maybe there are Weevils in the sewers nearby, or there’s a Carrionite church in the village down the road. Perhaps a Sycorax survivor has targeted your base for destruction. In any event, you face attacks from an implacable enemy on a regular basis.

The enemy always chooses the worst possible moment to attack. They will come for you when you’re already under attack, when your resources are overstretched, and when you’re running low on ammo and Story Points.