Leading Edge did the only two officially-licensed "RPGs" of sorts.
There's "Aliens: The RPG" which is incredibly, excessively intricate and has you creating a Marine character, although you can create other characters like corporate-based ones (corporate officials, corporate mercenaries, corporate spies, etc), or civilians, etc. The RPG also goes into a huge amount of detail about the Alien universe, going so far as to make up other (generally non-sentient) creatures that players could encounter other than Aliens, etc. The RPG came out before 'Alien3' did, so it only covers the first two movies.
The second one Leading Edge did was a tabletop wargame of sorts where you control one of the characters from 'Aliens' and reenact one of the battles (or make up totally new ones). That one even had little pewter miniatures and whatnot for all the characters; I actually have a set of miniatures depicting the Hadley's Hope colonists' "last stand", it's pretty neat.
You can play an online recreation of the tabletop wargame
here.