Aliens almost had a scene where instead of Amanda dying before she could reunite with her mother, she was still alive by the time Ellen was recovered. But, when Ellen attempted to contact her, Amanda accused her of Parental Abandonment and cut her off. Considering we don't get to see Amanda process her mother's message, it's possible her takeaway from the whole game is that conclusion.
Ricardo's Heroic BSoD after the synthetics wipe out everyone but him at the Marshals' Bureau is a tragic thing to see. He comes close to crossing the Despair Event Horizon, clearly shocked by what he saw, but no doubt feeling Survivor's Guilt of some kind for it. Amanda has to nearly shout at him to get him to just listen to her and try and compose himself again. If not for Amanda pushing him to continue helping so they both can survive, he likely would have given up and let himself die.
Ricardo's death is also pretty tragic since he's the character that works with Ripley the longest as Mission Control and is rightfully terrified the whole time. It doesn't help that he seems pretty young and frail compared to to the other characters. Amanda actually comes close to outright crying when she discovers his fate, which is by far the closest she comes to having an emotional breakdown in the game. Worse yet, the fact it isn't outright him dying, but getting Face Full of Alien Wing-Wong means that there is no hope for him, and that hopefully he at least died quickly when the station collapses and is destroyed.
Hopefully the Facehugger was still on his face - can you imagine the fear otherwise? Waking up... only to literally die as you do.
Sometimes you'll hear NPCs hiding from the creature, praying to God it doesn't find them and say they're not ready to die. Even if they were just shooting at you, it's still depressing to be reminded that these are people like you trying to stay alive, and that had the Alien not been a threat, they were probably decent people.
Some of the audio logs on Sevastopol can reveal some pretty sad stories; most notably the log called "Blood on my Hands" by Sinclair, chief of Seegson Security, which you encounter in Habitation Decks towards the end. On the log, a dying Sinclair reveals that the Xenomorphs have killed everyone, including his wife, and have taken his children as well, and that he was powerless to stop them. He then finishes by saying, "just send in the Marines or blow this place up. Take these creatures back to hell."
Marlow's rant at Amanda on board the Anesidora outright has him blame himself for everything that's happened. All he wanted to do was save his wife after the Facehugger got onto her, he had no idea what monster he brought back to the station by doing so. When he shouts that his actions are essentially what killed her and doomed the station, it's clear how much he's crossed the Despair Event Horizon and is desperate to undo his mistake.