When you are looking for Samuels in Chapter 12, you see him interacting with one of the hostile Working Joes. When it refuses to help him, he beats it down with his bare hands in 2-3 seconds flat, implying that all of the dead Working Joes you saw in this level — including the ones that had been torn in half or had their heads ripped off — were his doing.
Samuels in general, who is one of only a handful of synthetics in main Aliens canon not to turn on the protagonist at the behest of Weyland-Yutani. Out of everyone he is one of the few A.I. to actively assist humans against the xenomorphs. Here's to you Samuels.
Amanda escaping the now freefalling Gemini labs module: She turns on the airlock, hurriedly puts on a spacesuit, and lets herself be shot out towards the space station, all within a couple of minutes.
That wonderful feeling of power when you pull out your flamethrower and the xenomorph hesitates to approach you. It's short-lived, but after seeing the alien being basically invulnerable, this feels amazing.
There's even an achievement/trophy for it: "Back off!"
Watching the Alien go from charging you right away, to visibly waiting and snarling at you once it sees you have the Flamethrower after you use it on it a few times is a satisfying feeling as well. You can't kill it, but you sure as hell made it know you can fight back, and it now has to actively assess what to do about it when it thinks it had you cornered.
The scene of Sevastopol dying is Scenery Porn at its finest.
The introduction to the Xenomorph. Ripley and Axel have just run away from some guys and find a quiet area. Suddenly, Axel hears a sound and sees some sticky stuff on his arm. It goes dead quiet... and then a tail bursts through Axel's chest and carries him into the vent. Ripley goes to activate a tram, which seems to take forever, while you wait in a nearly pitch black room while the Alien continues to shriek in the distance and the music builds and builds and builds. And with that, the Alien became terrifying again.
In addition, the scene where it first comes out of the vent in front of Amanda in a cutscene and is now an active threat. The way it almost slithers out of the vent instead of just dropping, and its EXTREMELY close call with nearly finding Amanda is such a memorable introduction to what you'll be facing for the next 15+hrs. There's a beautiful, elegant horror to the thing that simply cannot be understated
When going through the hive, unhatched eggs will open if you get too close. If your timing is good, you can melee the facehungers coming out, killing them with a single hit from the maintenance jack, and making Amanda the only human in the entire Alien franchise who has killed a facehugger in melee combat.
While a huge case of Video Game Cruelty Potential and makes the area harder, it can be satisfying and even awesome to see hostile humans getting easily slaughtered by the Alien, especially if they attacked you first. Watching it essentially give them a karmic punishment for trying to kill you for no reason, and seeing it rush around as survivors flee or shoot it, really helps give the Alien a demonstration of the power it has.
Marlow won't stop with his plan to detonate the Anisadora; Taylor decides she's had enough, picks up a wrench and smashes him over the head with it. Given that he's not moving after, either she hit him so hard that he became unconscious or died. If it was only unconsciousness, he dies shortly after when his ship explodes, though from the blood splatter on Taylor's clothing after the act it's more than likely she mortally brained him.
Amanda's growth over the course of the game. She begins the game effectively as a terrified civilian just trying to make it through the hostile environment in search of answers but slowly molds herself into a survival badass as her options and crafting skills grow, playing a constant game of cat and mouse with the drone and foiling it every time. Is it any wonder the creature seems to take offense to her repeated survival? Seems like she inherited the same will to survive that her mother had.
