Turn based, no clock. Every morning you give each survivor one job: DEFEND the fence tonight, SCAVENGE a block for food, scrap or ammo, CLEAR a block of zombies to make it yours, BUILD the fence up, or REST. Every block you hold pays out at dawn and brings its neighbours to the fence after dark. Defenders and turrets shoot what comes; whatever gets through chews the fence. Everyone eats at dawn, morale drops when they cannot, and at zero someone walks. Hold eight blocks and the block is a town. Book IV of the Vesper Cycle.