Reduction is an original campaign for the game Alien Swarm.
Reduction is by myself, Tim Carter. Alien Swarm is by Valve. (And, to be clear, I'm not employed by or affiliated with Valve in any way. I'm simply a community mapper using the tools Valve has released to us, to make new content.)
Reduction is fully playable right now in beta. As of this writing it consists of four levels: Missions 1, 3, 4 and 5 (plus more than 50 custom props).
My plan is to build the remaining eight levels to complete the planned 12-level campaign. To meet this goal, I'm seeking crowdfunding. And if the crowdfunding campaign works out really well, I'll be adding a prequel and a sequel, both six levels each, as well as getting some (paid) custom work done (models, materials, particles, etc) by various Valve game community developers.
In terms of gameplay Reduction is designed to fit in with the Alien Swarm style of play: up to 4-player team-based co-operative gameplay. You are a squad of interstellar Marines; you have integrated voice-comms; you need to work together as a team, fighting hordes of crazed aliens to complete the mission objectives. Alien Swarm, by itself, is an excellent game - but it hasn't had a new, high-quality campaign in some time.
As a story, Reduction is wholly original and non-canonical. Alien Swarm exists in a classic sci-fi "bug hunt" style universe that bears a striking resemblance to the movie "Aliens" (which in turn was influenced by military-flavoured alien-invasion sci-fi stories such as Starship Troopers, Armor and The Forever War). Reduction taps into Alien Swarm's excellent gameplay and production values - but Reduction aims to tell its own unique aliens-invade-the-earth story.
In terms of look-and-feel, Reduction is very James Cameron-esque. The full campaign, once completed, can be summed up like this: Aliens-meets-The Terminator.
The question of the story is this: How much would you sacrifice if you found out our earth was being wiped out? Would you hide out in some bunker somewhere and count off the remainder of your days? Would you abandon your home to go live on some barren rock world, out on the fringes of the known galaxy? Or would you choose to follow a cryptic, self-appointed, possibly insane leader on a questionable mission to save the world?
But we're getting ahead of ourselves. These are things I can only hint at. The full story is written out now, and you'll see it in the remaining levels I'm intending to build.
I would even suggest that Reduction could be an entirely original IP franchise. With enough support, crowdfunding, and community enthusiasm, the plan is to turn Reduction into a standalone game mod, with new characters, unique new "aliens" and weapons. I could even see a movie and so forth, as there is a lot of background story developed that has necessarily been left untold in order to keep the focus on player-driven gameplay.
In fact, it would be cool if James Cameron himself did Reduction: The Movie. (Hey, no harm in dreaming big...)