Alien Swarm was originally an Unreal Tournament mod, and despite the developers being hired away to Valve, the team still maintained the passion for their game.

As it turns out, they have been allowed to take it further than just a UT mod, and the game has been completely rebuilt based on Valve’s Source engine, set to be released to gamers completely free.

The game is  top down shooter, that pits man vs. alien and is focused on team play through a four man co-op game style.

“Along with the game get the complete code base for Alien Swarm that features updates to the Source engine as well as the SDK. Alien Swarm adds 3rd person camera, depth of field, improved dynamic shadows and a wide variety of gameplay additions to the Source engine.”

• 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 and 8 unique characters
• Matchmaking, Steam Cloud, Steam Stats
• 64 achievements
• Tile-based map generation tool

Alien Swarm is completely free and available for download as of July 19th, 2010 via Steam. To get more details, visit http://store.steampowered.com/app/630/

Update: It wouldn’t be a true Valve release if it wasn’t delayed. In true Valve fashion, downloads of the game are currently unavailable, expected to open 2 hours from the hour that you are reading this.

See you online!