To be honest, assuming there is still a lot of assets and hardware around, the ONLY thing that a sequel needs to add is Multiplayer. Imagine a dedicated server hosting a large falling apart station, with like 64 player max, and 2 - 8 AI aliens running around. The online community is the perfect place to replicate people going crazy on a space station lol. All the team play, betrayal, trolling around and so forth. Just don't water down the environment, keep it interactive, and so forth. It would be like DayZ, but in a space station, and the Alien is a bigger threat than the players.