LoL at Halo being less 'geeky' than Star Wars, etc. Actually, now that I think about it, this could be a really cool mod. Basically, getting started as the flood would be real tough, but as they spread they become a real big danger. Then, I'd make several flood only combat oriented branches for the tech tree, since they are excellent at ground combat and at retrofitting other race's technology. What I'd do, if I was designing a Halo mod, is redo the tech tree so that colonization modules don't appear in the tech tree, but are given to the two conventional races. The flood might be kind of fun to make, though.
I think it is a huge, huge, shame, but that's the way it is. The problem is, at the moment people haven't really taken to parts design nearly as much as they have for total ship redesign. Since we've seen so few ships, you would need people to mostly design new parts that follow the design philosophy the races show in the halo games. I guess it would be possible, although it wouldn't really be all that easy, since Halo has focused primarily on ground combat, which is nearly absent in Galciv 2.