Armed with battle rifles, Smart Guns, flame-throwers, grenade launchers and, of course, shotguns for close encounters, your squad can shut down a single vanilla Alien without too much trouble, providing you master certain basic gambits like back-pedalling while shooting xenos to avoid their acid blood. But alerting one Alien alerts the entire hive, triggering a Hunt phase during which other Aliens home in on your position, while also kicking the aforesaid timeline into motion.
Your weapon of last resort is Retribution, an overdrive bar filled by taking damage, which heals and buffs your marines while immediately refilling your command points. Given a solid sense of priorities - should you spend those bonus points on a shotgun blast to stop a Drone abducting your Medic, or call in a dropship bombardment to flatten the Facehuggers massing behind? - it'll power you out of a corner like Ripley hijacking the APC.
Launching marine expeditions consumes a day, and every few days the planet's overall infestation level increases, making the maps more hazardous. This stokes pressure to finish each map's to-do list briskly and progress the story before the water gets too hot. Unlike in XCOM, the game asks you to reload a save when you lose a whole squad. But if you play badly, you might have to limp back to your APC and waste a day before completing all the primary objectives.
The AI does a good job of organising the troops, letting you respond quickly to threats without needing to micromanage, though you'll rely heavily on the slow-motion menu selection - given that the Aliens are, in some cases, actually swifter than the bullets you fire at them, I'm not sure Dark Descent would be playable without it. But the quiet genius of the whole-squad approach is also that it's unwieldy in a way that is true to the film.
A bigger issue is the game's cartoonish representation of the mental state of your marines, which tries to systematise the squad chemistry from the movie, but feels undercooked. As in Darkest Dungeon, your marines accrue stress in combat and sprout traits such as Bully which affect their and the squad's performance, obliging you to pack them off to the therapist between missions.