The Co-Op game Alien Swarm is now out on steam for free. The original game was developed as a modification for Unreal Tournament.
Valve Software (Half-Life Series, Counter-Strike, Left 4 Dead Series, Team Fortress 2) hired the mod-team and released the game
on the Source Engine, including all tools that are needed to make new maps and/or modify the game itself.
Game Facts :
-Tactical, 4 player co-op action game with a top-down perspective
-Complete game code and mod tools
-Unlock persistent items by gaining levels
-Over 40 weapons and equipment with countless loadout configurations
-4 unique classes…Read More
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And perhaps even do something more than just play it - make use of its SDK!
