
Alien Swarm
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Watch Alien Swarm for Alien Swarm by Valve.
Alien Swarm is a free-to-play, top-down cooperative shooter released in 2010 for PC. The core gameplay involves four players selecting distinct Marine classes to execute tactical bug hunts across an infested off-world colony, requiring coordinated squad-level planning to survive overwhelming alien threats using unlockable weaponry. This title uniquely provides the complete, updated Source engine code base alongside the game itself.

Valve
PC (Microsoft Windows)