World-Gaming Network – Alien Swarm review

Alien Swarm started as a Source mod that was originally based off an Unreal Tournament 2004 mod. Hundreds of these Source mods already exist on Steam, an example being the famed Counter-Strike Source mod. The developers of this particular mod worked on Left 4 Dead 2 and Portal 2, but were only signed on as official Valve staff for creating this mod. Because of its high degree of success within the modding community, Alien Swarm was publicized and released officially. Because more casual gamers are often turned off by the exclusivity associated with being a modder, releasing Alien Swarm at the almighty price of $0 was a great way to encourage Steam users to be more proactive towards Source mods.