Valve is legendary for its propensity to let its development cycles stretch out as long as the studio deems necessary to achieve quality; the policy is so notorious that it has been immortalized on Valve's official developer Wiki.

Now, barring catastrophe, the Half-Life and Portal creator looks to be setting a record for its shortest elapsed period of time between a game announcement and release, with the promise of top-down cooperative shooter Alien Swarm coming to Steam for free on Monday, July 19.

Along with the game, Valve says it will be providing the entire codebase for the Steamworks-integrated title, explaining that access to those materials will give prospective developers "more insight and examples for using Steamworks in game production."

The SDK for Valve's Source engine will also be updated on Monday, presumably with Alien Swarm-related changes.

Alien Swarm was originally a mod developed for Unreal Tournament 2004 and released in 2004 by Black Cat Games, which supported the mod with updates for several years, during which time it received numerous awards and honors.

In 2005, Black Cat announced it would develop Alien Swarm: Infested, a followup comprised of a new free version and a commercial product, using Valve's Source engine. Updates about the project on the developer's official site stopped in September 2007, and there were no new posts until just a few weeks ago.

Now, it appears that soon after that September 2007 update, Valve hired the Black Cat team to work on the Left 4 Dead series and more recently Portal 2, but the crew used their time "in between their contributions to the other Valve projects" to continue developing the Source version of Alien Swarm that will be released next week.

Valve has a strong history of hiring entire teams of developers responsible for games the company admires. Sometimes, as with the developers of Narbacular Drop and Tag: The Power of Paint, that results in internally-created games like the Portal series. In other cases, like Team Fortress, Counter-Strike, Left 4 Dead, Day of Defeat, and now Alien Swarm, Valve has used the hires to directly expand its portfolio.