A small citadel (concept map) image - Combine Prelude mod for Half-Life 2: Episode Two

Vladimir Ivanovich Alexandrovsky, a Russian citizen, was going home by railway when Black Mesa Incident occurred, after which he and his sister were teleported to Xen. They underwent fierce attack from the Vortigaunts and were forced to take the teleporter left by the Combine. They escaped and were sent to the Combine Overworld. The Combine promised to send them back to earth if they join their wars. They did so and the Combine carried out the promise. Later, however, the teleporter was used to invade the earth...