failing every quest
3:16 Carnage Amongst the Stars is more styled on Starship Troopers than Alien but it hits a lot of your bullet points. It's certainly worth checking out I think!
I checked out 3:16 and from what I can see it's heavily geared towards the narrative. Maybe I'm missing something? I didn't watch a live play.I think you'll have to abstract away a lot of what might be "traditional" combat rules -- movement, situational modifiers, range, hit points.
I thought of 3:16 as well, and a lot in that game can help, like:
* You want your damage rolls to be the number of Xenomorphs killed, not the amount of damage to a single enemy (straight from 3:16)
I'm going to try to go simulationist-lite I guess, that's how my rules set works. Range won't be a factor most of the time, and the GM would add in things like lighting and cover helping the xenomorph defense rolls.
Keep the difficult decisions falling on the players, and when they hum and haw they have to spend a die out of their dice pool to delay.
Agree that up close combat should be extremely deadly, but stat the xenomorphs correctly and shredding marines will just happen if they get in close.* Marines basically do not survive hand-to-hand combat with a Xenomorph - if they get to you, you're dead. I'd give 'em a plot point or two to get out of it (say, you get sprayed with acid, but manage to shuck off your body armor in time). (similar to "taking a hit on the armor" in 3:16)
* Objectives besides killing aliens, as mentioned already, are good: shutting down reactors, rescuing civvies, sneaky Weyland-Yutani "research" stuff on the aliens, etc.
* Lots of Colonial Marine extras to either get killed, or get taken over when a PC dies.
* Panic rules or stress rules, definitely. You want "It's game over, man!" moments.
Extra grunts is an interesting idea. I need to brainstorm what the extras should be capable of, in a very streamlined way, so that they add very little complexity to taking turns, but add a lot of flavor/options. The danger is that they would increase the PC-team firepower too much and the xenomorphs will never manage to get close enough for a kill. If the extras are temporary meat shields, then that's a fun resource for players gamble with.
The damage range for the firearms should be high enough so that the average hit is a kill-shot (especially with exploding rounds).
I will probably let players tell me the exact damage they inflict, but on my side of the screen round heavily: e.g. under 30 damage wounds a xenomorph, 30 or more kills it. I figure you just can't have gun fantasia if you have a nebulous "kills this many" but no stats tied to damage, rate of fire, facility in tight quarters, etc.
I'm hoping high damage at range for marines, high damage up close for xenomorphs will keep the combat from becoming a big hit-points-attrition slog.
One thing I want is players laying down heavy fire and then running out of ammo at inopportune times. Risk vs. payoff for every choice. Maybe a rising % chance every time a player lays down heavy fire that they inadvertently blow through their ammo.