Developing your own colony and spaceship should, of course, be a part of an Alien RPG. I would also add rules for developing your own space station (Sevastopol Station style). It should be possible to just add more modules (and other stuff too). It could also be cool with rules for running your own crime syndicate with dens, brothels, corruption, gang territories, space heists etc. A more bizarre take would be to develop your own xenomorph hive and nest, assuming that the PCs are xenomorphs.