Terminus 9 is an underground transit and freight hub buried beneath the old colony district, built to move cargo, people, and emergency supplies below the water table. Now the valleys above it have turned into sulfidic bog, and the abandoned station below has become a subterranean forest of Sourstacks. The Sourstacks are alien fungal towers rooted through the wet infrastructure, coating the concrete with hooked biofilm, corrosive sludge, spores, and lethal gas.

A small sapper team is sent down into Terminus 9 to recover two hundred anti-toxin ampules from a sealed medical vault before the poisoned battalion on the ridge collapses. Every movement through the hub becomes a contact hazard: flooded corridors, failing seals, black sludge, and touch-sensitive biofilm leave no room for mistakes.

When ...