Combine Wall



Seen surrounding the Citadel and certain areas of Nova Prospekt, mobile walls are actually machines, using powerful drive systems in tandem with heavy metal blocks to slowly expand outward and destroy existing structures in the way. Standard operation is to lift and force a set of blocks outward, before allowing them to drop, and then alternating with another set. Some believe this is the Combines' way of harvesting raw materials for other purposes such as Synth creation and the construction of other vehicles and Citadels.