Mechanism: Construction Tree This page visualizes the hierarchical relationship between base constructions and their prerequisites. Barbed Wire Perimeter Reinforced Steel Bulkhead Spike Trench Scrap Barricade Wall Timber Palisade Wall Kill-Zone Floodlights Auto-Bolt Nest Shock Fence Grid Armor-Plated Gate Sensor Jammer Grid Counterbattery Array Citadel Aegis Core Scrap Workshop Automated Sentry Watchtower Signal Booster (Radar) Beacon Amplifier Well Hydroponic Patch Solar Panels Research Lab Research Lab II Battery Storage Fuel Refinery