Bad ending could lead to interesting sequel scenario set in dystopian Sirius where upper echelons in league with alien benefactors, the story of espionage, betrayal and obligatory rebels fighting to thwart alien oppressors.
Wait a second...
Freelancer: Half-life 2!
...and PROFIT!
p.s. almost makes me want to forget things done here and go do something really interesting in that setting, getting tired of going nowhere here (thinking loud).