The Obsidian Hammer

You are a master stonemason of Tenochtitlan, accustomed to shaping the grand aqueducts and sanctuaries of the imperial city. But on the wet, blood-soaked night of June 30, 1520, the retreating Spanish conquistadors attempt their desperate midnight flight across the Tacuba causeway. When the vanguard leader falls beside you, you drop your chisel to wield a dead warrior's obsidian blade. With every portable bridge destroyed and the surrounding lake churning with combat, the fate of Mesoamerica hinges on a single tactical divergence. As counterfactual history unfolds beneath your feet, you must forge a ragtag defense into an unyielding shield. Can a gentler builder transform himself into the decisive commander Tenochtitlan needs, or will the crucible of total war destroy the humanity you seek to defend?