1. The Aliens weapon-set
Watch Aliens and make a list of the guns you see the Colonial Marines use throughout the course of the film. Pistol, shotgun, assault rifle, pulse rifle, flame thrower, grenade launcher. That's the list you'll end up with. And what is that list, if not the traditional FPS weapon hierarchy, as standardised by id Software between Wolfenstein 3D and Doom?
2. The 'countdown to destruction' ending
Alien, Aliens and Alien Resurrection all end with Ripley making a desperate, seconds-to-spare run through an exploding, siren-honking facility during the countdown to its solar-system-searing detonation. Games play with this set-piece a huge amount, particularly as a post-final-boss climax. Metal Gear Solid used the idea, and Resident Evil has used it so many times that its become a series trope. And as for Super Metroid, is it any coincidence that 'Aran' sounds like someone mumbling 'Ellen' with a mouth full of biscuits? We think not.
3. Air vents
The dark, creepy air vent crawl has become a long-standing FPS clich, albeit one that still elicits a quiet Pavlovian dread response in all who approach it, dating back to that long-suppressed incident involving the headcrabs and the involuntary urination. And to be fair it makes a lot of sense as a game mechanic.
4. White cyborg blood
The Alien series established early on that not only can lifelike androids exist, but that they must be fuelled with nothing less that a 50/50 blend watered-down natural yogurt and carbonara sauce. White blood is the de facto filling for walking, talking robo-men and, wouldn't you know it, the same is the case for Metal Gear Solid's slicing, dicing robo-Raiden.
5. Sgt. Apone
Halo's Sgt. Avery Johnson is an entirely original creation and any similarity to any pre-existing characters in the Alien universe is purely coincidental.
6. Mobile gun turrets
Since Half-Life 2 gave environmental interaction a stout, HEV-booted kick up the arse, deployable defence turrets have been a staple part of modern FPS tactics. They're standard issue in BioShock 2 and Team Fortress 2, a core combat element for Borderlands' Soldier class and a weapon perk in Modern Warfare's multiplayer. But however many suspiciously Xenomorphous Antlions Black Mesa's finest might have turreted to death in the gloomy tunnels of Half-Life 2: Episode 2, Corporal Hicks will always be the guy who did it first.
7. Facehuggers
Almost every sci-fi or horror game has a small, horrible, skittery bastard of an enemy that makes up for its high burstability rating with a nasty turn of speed and a major penchant for jumping at your head with its mouth open. And all of them, whether headcrab, metroid, springing zombie leech, or that godawful upside-down human head spider thing in Doom 3, are inspired by Alien's Facehuggers.
8. Insane secondary fire options
Okay, so real, modern-day military rifles do sometimes come with attached grenade launchers or under-slung shotguns, but games are outright obsessed when it comes to fitting out already fantastic guns with ludicrously powerful, totally incongruous and gloriously unnecessary secondary attachments.
10. The Aliens themselves
There hadnt been a monster like the Xenomorph before Alien. So intrinsic was the idea of using an H.R. Giger monster to Dan OBannons script that the organisms unique and horrifying nature cut through the films atmosphere like a sharpened bio-metallic tail-barb. Part lizard, part insect, part nightmare, and displaying the cold, unrelatable predatory instinct that all that entails, the Alien is so unique in its physicality and traits as to be one of the few monsters in its genre to be truly alien.
11. Biological environmental design
The problem with being a unique visionary artist with an original aesthetic all of ones own in that it once your work stuns the rest of the world with its impact, it takes the rest of the world all of about 14 seconds to make your shockingly fresh aesthetic appear old-hat by ripping it off in various shamelessly derivative configurations.
