I got AliensRL only recently and played it just a little bit, so I can't comment much on the gameplay yet, but just as a couple words on the lore, in the first movie Weyland-Yutani knew about the existence of the Xenomorphs. They were planning to capture a specimen and bring it back- with or without the crew. Ash was there precisely for this reason.
Thus in the second movie the presence and existence of Xenomorphs are pretty well known to the corporation. You also have to remember that Aliens was a movie of the 80's, and therefore W-Y is the big evil corporation first and foremost, logic comes second. That's why Burke's motivations are not completely clear, as in was he also ordered to bring back specimens? Did he act on his own? Why were colonists sent on the planet in the first place despite the presence of Xenomorphs? How come no one saw the Space Jockey craft before? etc.
As long as the "evil corporation plays around with dangerous things, bad things happen" is applied, writing some vague motives should be easy enough. And from there it can go further.
Motion scanners BTW are a must. Alien hissing sounds can be toned down and in place of that the motion scanner's detection scan and detection sounds could be more prevalent. Xenomorphs are normally very silent, unless they have been seen someone and are going to attack. They are supposed to be relatively fragile but very dangerous creatures. So the motion scanner would add tension to the game, if for example it would have false readings or erroneous number of signals, like in the Space Hulk game.
Also maybe the game could be more oriented towards survival and escaping with minimal losses instead of being more combat oriented? Like in the first movie wrather than the second one.