Ooh, Alien Swarm needs two things. One, a FS Hallfight-style mod, and two, a 40k mod since we don't have enough Space Marines killteams in video games. A Captain, Apothecary, Techmarine, and Devastator would fill out the slots nicely. Don't mention the Imperial Guard, since sending them in is an all-you-can-eat-buffet for the aliens, even if they're Stormtroopers. Or, there could be a SST mod based off Terran Ascendancy, which is an RTT game inspired by both book and movie.