B/X Known World
Cool. Thanks for the detailed replay. I can see why you have trouble finding lighter systems you enjoy. It seems like your minimum amount of rules is somewhere in the medium to medium-heavy range.Suitable abstractions: this is very much a setting trope issue.
Let's take Alien (the setting), Alien (the Movie), and compare the current RPG (ALIEN: The Role Playing Game), the older Aliens Adventure Game and it's closest thematic game with official (for the game) stats I'm aware of: Classic Traveller (henceforth, Traveller, or CT).
Alien as a setting is pretty clearly space truckers and marines as protagonists; things we don't know how to do, but the characters do, exist in the setting. We also know there are scientists, and stress leads to lasting traumas. We see two different forms of AI - MU/TH/UR and the Synthetics.
Alien, the Movie, shows us the computer bringing them out of both FTL and Coldsleep with minimal supervision/intervention. We also don't see MU/TH/UR go all HAL-9000 on them, either... it gives them the mission orders, and keeps tabs, but doesn't try to interfere when they decide the "prize" needs to die. We see a synthetic, Ash... He's sympathetic, in both senses - he feels sympathy to a point, and he's a character we can feel sympathy for... We also see the effects of increasing stress on Ripley (Weaver) and Dallas, and even to a point, on Ash. We see people fighting on despite injuries. We see more of this in Aliens.
Traveller has rules for Cryoberths - but they need medical attention to come out safely. Traveller's rules for FTL are plenty workable, but make different assumptions than the indicia released about the setting give, vs the standard ship in Traveller having a parsec range, tho' Traveller's jumps also take less time. Traveller's rules for AI put it at a tech level beyond the rest of the tech we see in the movie or indicia, and aren't particularly robust, either. Oh, and the stats for the Alien? Reticulan Parasite, JTAS issue 4, page 26. In Traveller, it's a nasty parasite, matching the screen... but it's handled as a smart animal. There's no stress rules at all in CT. Traveller's closest thing is Morale - and by the book in core, it's for NPCs only. (Book 4, which is supplementary, adds morale for PCs.) With Book 4, the ACR is a near perfect fit for the Pulse Rifle of Aliens, and by inflicting morale on PCs, can easily replicate the fights from all three core movies... but not the rest of it. Traveller lacks abstractions for social actions. It also lacks descriptive critical injuries. Classic Traveller's interpersonal skills are few: administration, bureaucracy, liaison, steward, and carousing. None of them are "persuasive" in nature. Admin and Bureaucracy are both about getting things done. Steward is how to keep passengers out of the rest of the crew's hair, not convincing them. Carousing allows getting information... but is as much about boozing as info. Liaison is a hybrid of Admin and Bureacracy... so the abstraction is for purposes commercial, rather than actual interpersonal.
Alien: the RPG, (A:TRPG) for its part, makes cryo only need attention when there's injury, tho it does have downsides that CT lacks (MT has them in a magazine article, TNE has them in core). FTL is long and mentally hazardous, plus reduces cargo capacity a lot due to food needs. Travel is usually broken up by a number of stops to perform routine maintenance.
Stress is mechanicalized. Abstracted into mechanics... a little stress lets you exceed your normal limits; a lot breaks the PC in strange ways; further, it has two different stress failure tables, and they're tailored for different regimes of play; I expect another one in the new book, too... The alien from the film is one of several in the core. The Xenomorphs are a clade, not a singular thing. This is different from the movie, but is a known thing in later setting materials. The game can easily also handle all the action in Aliens and Alien³. It can abstract out Ridley getting Newt out from the vents if needed; and the social conflict mechanic can be resolved as a single roll.
The Aliens Adventure Game, (AAG) from Leading Edge back in the early 90's, has excellent (if slow to run sans spreadsheets) gritty combat, but only one flavor of xenomorph; it has other nasty critters to bug hunt, too, but seems to expect importing more from Phoenix Command. Its rule for cryo are more generous than Traveller's or A:TRPG. It has morale rules; I don't recall, and am not going out at 3 in the morning to get the book from the storage, if it has stress rules otherwise. It has a hard 8 LY limit on each jump. It's Xenomorph is almost too hard to kill. It presumes only Marine PCs. It's narrow, it's crunchy as hell, and only combat is handled by mechanical abstraction in any fidelity, but it does have interpersonal skills, and some rules on using them to influence others. Nothing even approaching a full on social combat system.
As for #3? short term injuries, long term injuries, death, and/or insanities are the suitable ones for the Alien setting. Traveller has only 2 of the 4, AAG has 3 of the four. A:TRPG has all four...
In A:TRPG, in one campaign, one PC, entirely without ever facing any xenoform, drove herself to a nervous breakdown. As in, total catatonia. Replacement character followed. For that character, life as a ship's mechanic was too much, and she pushed on until she broke. (The player completely forgot to, or perhaps decided to see what would happen if she didn't, take those rest times to destress.)
ETA: Thinking about it more, Fate Accelerated would fit all your criteria.