Valve unleashing free Alien Swarm

Portal 2 may be Valve's big release for the year, but it apparently won't be its only one. The Kirkland, Washington-based developer has now added Alien Swarm to its 2010 docket, announcing this week that the game will be out for PCs…on Monday. What's more, it'll be completely free through Valve's online distribution portal, Steam.

Developed in-house by a team hired from Valve's mod community, Alien Swarm is a top-down 3D shooter developed using the Source SDK engine. The squad-based tactical shooter accommodates both single- and multiplayer action, where up to four players can choose from a quartet of IAF Marine classes to hunt down and slaughter alien bugs. Players can also choose from eight different character skins.

Alien Swarm offers more than 40 unlockable weapons and war accoutrements to help players in their interstellar bug hunt. Gamers will also be able to unlock persistent items as their characters gain levels. Environments in the game run the gamut of icy surface terrain to underground, lava-rich mining facilities.

With the release of Alien Swarm, Valve will also be offering the game's complete code and mod tools to the development community. As with the game, the code will be available free of charge.