I don't understand why people have to label Ripley as either macho or as the standard frail horror movie heroine. To me Ripley kicked so much ass, because she was neither. She always seemed like some average working woman, who maybe had a husband and kid somewhere waiting for her to come back from her mission. She wasn't a 20-something supermodel, but then again she wasn't made to be like Vasquez, she just happened to be a common everyday woman being thrust into a situation that was way beyond her control. And then just trying to make the best out of the worst situation. At least the first movie was very neutral about it, not trying to make a fuss about if she was a he or she or a tranny or what have you.
Also the fact that even if Ripley didn't ever seem like a killing machine, at least she always seemed somewhat competent and able to get shit done. That said, I'm throwing an educated guess and say that the protagonist in this game is going to at least some point go OHGODOHGODOHGOD, whine and whimper, be a complete pussy and still end up killing 100+ aliens.
Plus, most of her characterisation is in the 1st movie, which is even more of an ensemble piece than Aliens. Weaver didn't even get 1st billing - that went to Tom Skerrit (which, admittedly is a little bullshit). She's very much just one member of a very blue collar salvage team, with her most 'heroic' quality being that she's very level-headed through-out (though so are the others, with Skerrit's Captain Dallas being the most classically 'heroic' - a decent bait-and-switch when he gets killed halfway in). Parker and Dallas are the only real 'badass' characters, and even they aren't badass in a soldier sense - more in the sense of Parker being a 'I"m going to survive this fucker' personality and Dallas being a very engineer-like captain who's determined not to let this thing take down the ship (and has an unfortunate willingness to go into dark places wielding only a glorified blowtorch....).
Actually, scratch that. The biggest badass in Alien is the ship's cat, by a looong fucking way
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Even in Aliens, Ripley is deliberately juxtaposed against both the soldiers and the executives. Note how they make a point of her asking if she can make herself useful, and volunteering to drive the loader. Obviously that's there as groundwork for the ending where she uses the loader to grapple the Alien queen - but it's also character-work, playing her like she is in Alien as someone who's spent her career in blue collar salvage-type jobs where she's part of a tight crew, but not some soldier or adventurer-hero.
People (and later sequels) put far too much focus on the last part of Aliens, where she goes all-out to save Newt. Before then, she never even engages in direct gunplay - Hicks actually teaches her to shoot midway through that sequel (making it a film and a half in before she fires a gun, and almost 2 films in before she fires a gun AT something). Also, she isn't exactly mowing down legions of xenos on her way - it's a lot clearer in the director's cut, but when you count the number of colonists (and hence the maximum number of xenos), the xenos have lost most of their force by the time she goes looking for Newt, hence she gets almost an entirely clear run to the Queen.
In any event, that's really just 'last act heroics', not central characterisation work. For most of 2 films, she gets shit done because she keeps her head and is a good engineer who quickly recognises mechanical threats (e.g. that they need to race to stop the acid reaching the hull in Alien, and realising that the marines are too close to the nuclear reactor in Aliens).
Nonetheless, the cat has more common sense and general survivability than the rest of the franchise's characters combined. If only he had opposable thumbs, he'd have gone 'fuck these morons' and bailed in the escape pod the moment they took Kane back onboard despite being contaminated by an alien lifeform.