Alien Swarm has arrived on Steam in all of its top-down glory. The game - which is available free of charge - features a "unique blend" of co-op play along with squad-level tactics.
"[In] Alien Swarm, you form a squad of four distinct IAF Marine classes. Attack [are planned] using an unlockable arsenal of weapons with countless loadout configurations against a wide variety of aliens," Steam explained in an official statement.
"Blaze your way through an overrun, off-world colony, eradicating the alien infestation in environments ranging from the icy planet's surface, to a subterranean lava-flooded mining facility."
The game also boasts third person camera perspective, depth of field, dynamic shadows and 4 player co-op with a "top-down" perspective.
Additional features include:
Alien Swarm, along with its accompanying source SDK, was created by a group of talented Valve designers originally recruited from the Mod community.