Some of you may remember Alien Swarm . . . it was a mod for Unreal 2003 that had you playing a squad of marines who land on an off world colony that has been taken over by parasitic aliens . . . and yes, the plot was lifted nearly verbatim from the fight scenes of James Cameron's Aliens.
The gameplay was super fast, scary, tactical . . . and above all, super hard. As a house, we struggled through the campaign, with lots of glorious moments of yelling and screaming among nail biting finishes of missions and desperate rushes through seemingly unlimited numbers of aliens.
And we thought the fun was over . . .
The team that made the mod was picked up by Valve, and later did some work on Left 4 Dead, bringing their experience to that game (and probably helping make it into the amazing game that it is). The beautiful thing, however, is that they never quite left Alien Swarm behind and have been working on it in their spare time. The new game is finished and it comes with so much icing on top . . .
The new source engine version of the game is going to be free to download, and they've also included all their source for it, so you can modify it to your heart's content!
Bring it on!