Asper Alien vs. Predator (2004), every 100 years the predators come to Earth to hunt aliens (xenomorphs). The predators use humans as a way to harvest xenomorphs. This has been happening for thousands of years.
It's not a war. Predators hunt xeno because they like hunting. In the first issue of Aliens vs. Predator we can see that predators keep queen and then send her egg to different planets (chosen by predator) to create hunting ground.
Because of the constant change in settings between movies and comics we can only assume that Predators been hunting for something for a very long time and when Aliens came to existence they switched to hunt mainly for them. Using humans as a host because humans (until movie Alien3) turned into Warriors. In Alien3 they established that xenomorphic take some characteristic of their hosts.
Alien vs. Predator is the combination of Fox's two hit alien monster movies, and the stories of the innocent humans caught in the middle. The series started with a comic by Dark Horse Comics, featuring colony administrator Machiko Noguchi, who finds her newly-settled world has just become a hunting ground for the Predators as they seed it with Xenomorph eggs. Dark Horse would follow on this with other comics, such as Deadliest of the Species and War, as well as crossovers with Superman, Batman, and even The Terminator. Riding the popularity wave of Predators, the Machiko story was picked up again in the mini-series Aliens vs. Predator: Three World War, in which the humans and Predators team up against a second race of Predators (similar to the "black" ones from the film) and their Alien pets.
The concept was even hinted at in the second Predator movie, which featured a Xenomorph skull amongst the Predator's trophies. It was finally made into a movie in 2004, with a sequel in 2007. The movies abandoned the previous setting and had the conflict take place on contemporary Earth. That the movies weren't exactly embraced, even by the fanbase, owes more to the fact that the movie's Human protagonists were the weakest element and simply weren't credible enough, as well as a PG-13 rating limited the violence. The Aliens and Predators remained both on form.
A number of video games have been made; along with a series of comics and novels, they are completely unrelated to the story or setting of the movies. They are instead set in the same time and setting as the movie Aliens.
A-M Abnormal Ammo: Radioactive ammo from the RTS. Spider mines! The standard ammo for the pulse rifle. It's 10mm, larger than mostly any ammo used for rifles, case-less, armour-piercing and explosive. When it comes to fighting Xenomorphs, this is essentially the kind of ammo you need to put a dent in them, as Aliens showed us them shrugging off pistol shots like nothing, and in the 2010 Rebellion game, using the pistol against a Xenomorph is asking for an overdrawn engagement. It usually takes the better part of the pistol magazine; over a dozen rounds. And that pistol's an upgraded one designed to be halfway effective against the buggers. Predators get this in general, especially with the second PC game. Most of their weapons are abnormal and require some form of abnormal ammo, starting with energy as described above, all the way to nets and spears made of substances not found on our periodic table. The Predators can also turn electricity into plasma. Aborted Arc: Aliens vs. Predator 2 and Aliens vs. Predator (2010) both end on cliffhangers that never got followed up on, due to the series either rebooting or being put on hiatus immediately afterwards. Absurdly Spacious Sewer: the 2010 game. Also invoked in Av P Requiem, the city of Gunnison (in Colorado, real life population of about 6300 people) having a sewer system large enough to walk around in. A Commander Is You: Extinction and The Hunt Begins both balance the three factions in roughly the same way. The Colonial Marines are the Balanced/Ranger faction. They have more units on the field than the Predators and a gun for every occasion, but they're practically helpless in melee. The Aliens are the Spammer/Unit Specialist faction. They can have more units on the field than the other two sides combined, and they typically have units that have evolved to fill certain niches more effectively than anything else. That being said, they have little to no ranged options to speak of, and their more common units tend to be more frail than any of their equivalents from the other factions. The Predators are the Elitist/Brute faction. While they do tend to have a trick or two up their non-existant sleeves, the overall schtick of the Predators is that they have just flat out better units than the other two species but can't field even half the amount of units. Action Girl: Machiko from the comic and Linn Kurosawa from the Arcade game. Dunya the Iron Bear mercenary from AvP 2 (the game) and its expansion pack. Tequila from the 2010 game. Lex from the first film, after a bit of a warm up. Admiring the Abomination: Most major antagonists, such as Dr. Eisenberg and Karl Bishop Weyland. Inverted with General Rykov; he already hates the Predators, and the more he learns, the more he abhors them. Air-Vent Passageway: Alien players will see the interior of a lot of ventilation shafts. The Marine player in the second PC game also does this. Alternate Continuity: Features a different timeline than the timeline in Prometheus. And I Must Scream: Dr. Eisenberg in AvP 2. His arms and legs are torn off, cocooned into the wall of the Queen's chamber, and since he's a synth, he can't die. The Alien campaign ends with his hysterical shrieks echoing throughout the dark burrows of the hive. Anti-Villain: General Rykov in AvP 2. Although he's happy to secretly kill a few Weyland-Yutani civilian employees (the people he's hired specifically to protect) in order to steal company resources for his mercs, and under Eisenberg's orders sets the Marines up for an ambush to wipe them out, he's clearly not taking any pleasure in doing so and is absolutely loyal to his own men, even going so far as to undergo a suicide mission at the end of the game to buy time for his surviving mercs to escape the planet. He also ends up indirectly helping the Predators (even though the last time he encountered them, they blasted a hole through his spine). Apocalyptic Log: Most of the backstory for AvP 2 and the 2010 game is told through memos and Incident Reports seen at the start of each level. They even foreshadow what you're about to run into next. Arm Cannon: The Predator "Topknot" in AvP: War is shown with a wrist-mounted plasma caster. Asshole Victim: The human you eventually have to impregnate as a facehugger in AvP 2 is beforehand shown to be a complete asshole of a sergeant who constantly bullies his subordinates and shirks his own duties. You won't feel all that bad for having to chew your way out through his ribcage. Asskicking Leads to Leadership: In the 2010 game Weyland comments that the Aliens are a "true meritocracy." Given what Aliens do, this trope applies to the entire species. The Predators go by this, too: if you want to get anywhere in this society, you have to prove your combat chops in the hunt. Preds often settle disputes in bare-knuckle brawls as well for the viewing pleasure of their fellows. This is proven at the end of the Alien scenario, where Six "evolves" into a Matriarch... Unless you realize that at the end there's pretty much nobody else to 'promote' to the position in question. A scientific log in the second game on how the heavily armored Praetorians develop also fits here: When an alien drone begins the change, it secretes pheromones which causes other aliens to attack it violently. Thus, in order to become a Praetorian a drone has to be tough enough to fight off other aliens en masse, and intelligent enough to escape and remain secluded until the transformation is complete. Authority Equals Asskicking: Karl Bishop Weyland in the 2010 game; in the final shootout of the Marine campaign he can kill you in just 2 shots and can survive even more damage than an elite Combat Android, taking almost a full 99 round magazine from the pulse rifle to bring down, although he still goes down after about 14 shots from the semi-auto sniper rifle or 5 good shotgun blasts. The Alien Queen and Predator Ancient in the RTS. The Ancient can insta-kill all enemies under 50 hp within arm's length. The Queen is no pushover, even in her default form, but the upgraded form has more armor, and sends all transbreed aliens into a killing frenzy. It's a totally viable strategy to assault a base with the Queen leading the charge. Averted with the Commtech marine, who is almost defenseless before being upgraded, but is still a bit of a Glass Cannon after. Awesome, but Impractical: Both PC games feature a rocket launcher as part of the Marine's arsenal. That's all very well and good, but not much use when 99% of the enemies you face are fast-moving, melee-oriented aliens. The kill moves in the multiplayer demo for the 2010 game are awesome looking, but leave you vulnerable for some time; its not that uncommon to see an alien grab a marine, with another alien behind him, etc cetra, forming a conga line of blood and gore. This applies in single-player too when fighting multiple enemies, too. The Marine's flamethrower is cool, but doesn't actual deal direct damage, and it takes an alien several seconds to burn to death during which they'll happily attack you. The 2010 game is even worse, as it retains all the flaws of the version from the 1999 PC game, eats ammo for breakfast, and now a burning Alien can grab your leg and kill you instantly when it explodes. In AvP 2, the flamethrower didn't really set enemies on fire, but it did deal massive direct damage and could kill a xeno in a split second. It's very effective against Facehuggers though. In the 2010 game, the Predator's plasmacaster auto-locks onto enemies and can gib a xeno or marine with a single charged shot... and you can only fire about 3 or 4 charged shots before running out of energy and being unable to fire until you found an energy pickup. The Primal Hunt expansion allows Major Dunya to carry and deploy up to two sentry guns. Unfortunately, the turrets have poor tracking, do surprisingly little damage and are destroyed by any amount of damage whatsoever, incluiding the acid blood of the very aliens they might be shooting at, so don't count on them to cover your back. Besides, most enemies spawn pretty much on top of you, so you rarely have time to actually deploy them. Backported Development: The NECA homage toyline to the Kenner figures incorporated elements from later movies, including making the Nightstorm Predator a Black Predator from Predators and Scavage Predator (a redo of Nightstorm) a Classic/Black hybrid. NECA even as far as to make figures of the Berserker Predator from Predators and the Neomorph from Alien: Covenant in the style and scale of the Kenner line. Badass Normal: Given the... nature... of the other two primary combatant species in the PC games, the anonymous Marine and Corporal "Frosty" Harrison from the games definitely count. Hell, Harrison repeatedly takes on entire hives of Aliens by himself and kills a particularly vicious Predator that took out most of White Team. As for the anonymous Marine of the first game, well. Balls of steel doesn't even begin to cover it. The "Rookie" from the 2010 game, who gets stranded alone in alien territory at least once per scenario and he still manages to fight his way out, including at one point getting captured by the Aliens and having to escape through the hive . It's worth noting that nearly every character in the game expresses disbelief that he has somehow managed to survive. Bag of Spilling: No matter what you end a mission with in the 2010 game's Marine campaign, you always start the next one with a Pulse Rifle in one slot. And at one point you lose that, too. Averted in the Marine's final battle; there's a cutscene which seems to imply the Marine has lost all his weapons except his pistol, just before he has to fight some of the toughest enemies in the entire game. In fact his previous weapons are simply holstered, and he can pull them out at any time. In the RTS, even if you ended the mission with an army, you'll start the next with a handful of units. Occasionally explained in the Alien story, with situations such as a Queen starting a new hive, or a recently decimated hive trying to reclaim its captured Queen. BFG: Lots of these. The Minigun, kill-a-Praetorian-in-one-hit sniper rifle and military power loader in 2 come to mind, and the 2010 game's Smartgun is so big it takes up both primary weapon slots. Bittersweet Ending: In AvP: Three World War, Machiko is able to defeat the rogue evil Predators, but her refusal to die fighting causes another Predator to burn her "status symbol" forehead mark with more xenomorph blood. She's no longer able to work with the Predators, and humans in general are back on the hunting menu. However, Machiko has overcome her issues with isolation and is living happily with her lover, and the evil 'Killer' Predators have been defeated, if temporarily. Blue-and-Orange Morality: Most Predators aren't actually evil. Their morality and values system, however, is insanely incomprehensible to humans and they're merciless hunters towards worthy prey. Body Horror: We all know how revolting that scene in Alien with the chestburster eating its way out of John Hurt's chest was, right? Well, in the second PC game, you get to play as the chestburster. Then you have to eat a cat. In the expansion, not only are you the chestburster, but your unfortunate victim is the Predator you play as in the Predator campaign. The Xenomorphs in Extinction weaponize their unique biology, including one ability that digests enemy units alive and stores the resultant Health Food as cysts so that the Chest Burster they spawn can metamorphosize into a King Mook. Boring, but Practical: In Aliens vs Predator 2, the video game, the regular old pulse rifle qualifies as this. It appears to be, at first, just another generic assault rifle. After about two missions of using it you will suddenly realize it kills all common enemies in as many as 5 shots, has a magazine of 99, a rate of fire close to a modern AK-74 assault rifle, possesses an underslung integrated grenade launcher (with perfect trajectory and quick travel times) which instagibs nearly everything in the blast radius, and there's a bug which causes the first bullet fired to cause extra damage, thus making burst shots more powerful while saving ammo. The icing on the cake is that it is available to humans throughout almost every mission, with abundant ammo to boot! Three guesses as to which human weapon received, arguably, the most use in multiplayer. The Alien pounce attack also fits; It's nothing more than a single button move where you fling yourself through the air at a high velocity. Upon impacting other living things they are instagibbed or stunned in place, leaving them open to a quick and brutal slaying. In multiplayer the pounce 'n' slash became the bread and butter of every xenomorph player. Borrowed Biometric Bypass: In the 2010 game, the Predator has to use some unfortunate guy's severed noggin to open doors locked by retinal scanners. Boss Arena Urgency: The battle between the Predator and Predalien in the 2010 game takes place over walkways slightly above lava. As the battle goes on, the Predalien will start to cause a cave in, wrecking the walkways so that the player has to both make tricky leaps between platforms, and at the same time fighting the Predalien. Bowdlerize: The SNES version changes the nightclub in Stage 3 to a cavernous area. Canon Discontinuity: Ridley Scott, who disliked the crossover franchise, completely de-canonized the Alien vs. Predator film duology with Prometheus and Alien: Covenant. Furthermore, FOX jettisoned the Praetorian caste from canon with Alien: Out of the Shadows. Canon Foreigner: The predator warrior and the planet Vega 4 are not mentioned outside of the SNES game. Linn Kurosawa, the two predators, the cyborg iteration of Dutch Schaefer, and the city of San Dorado are not mentioned outside of Alien vs. Predator (Capcom), though Linn Kurosawa has made cameos in a few Capcom games. Canon Immigrant: The PredAlien goes from a enemy in the PC game, to having its own campaign in the second game's expansion, to an official sub-species in the second movie. There's also the different vision modes the Predator uses to spot aliens instead of humans in the first movie, that in turn was an explanation of the vision modes used in Predator 2, where it found the heat-cloaked humans by switching settings. Also shown briefly in the original Av P comic, where Broken Tusk gets his mask back, and sees several of his Predators fighting invisible enemies. He switches view modes, and now the aliens are visible. When taking into account ''Aliens'' implying that Xenomorphs don't show up on infrared at all, and the Predators naturally see in infrared, this would be a necessary feature to successfully hunt them. The 2010 game in turn incorporates a few elements from the first AvP movie (the Predator pyramid, Alien Vision mode being green instead of red, Charles Bishop Weyland) as well as from the AvP 2 game which was made by a different developer (Combat Synth Elite Mooks, Runner aliens, a shotgun and sniper rifle, and a Corrupt Corporate Executive Big Bad who turns out to be an android). Canon Welding: The intention of the movies, until Prometheus established a different timeline. Checkpoint Starvation: Nightmare Mode disables the checkpoint system, meaning you get bumped back to the very beginning of the mission if you ever die (which, given the enemy's increased damage output, happens a lot). Chekhov's Skill: In the intro to the marine campaign in AvP2 Frosty is shown moving around cargo with a power loader. This gives a subtle bit of foreshadowing to that he is probably qualified to operate the military exosuit, which he indeed does near the end of the campaign. Clone Degeneration: This is an in-game theory presented as to how, over the course of several hundred years, Weyland went from a reasonably Reasonable Authority Figure in the present day to the Card-Carrying Villain he is in the far future of the 2010 game. Colony Drop: The W-Y installation on LV-1201 is designed around "Pods" suspended from a ginormous superstructure. If one Pod is compromised by, say, the alien lifeforms you're running unethical research on, you can just jettison the whole thing before the infestation spreads. Machiko does this in the first comic, almost literally. She runs a colony on a desert planet, and a ship has just arrived to take the rancher's herds offplanet for processing and sale. Like the Nostromo in the first film, it's basically a tug with a large slaughterhouse attached, and the bigger part stays in orbit. Machiko crashes it into the colony to wipe out the alien infestation. Continue Your Mission, Dammit!: The 2010 game's Marine campaign does this rather a lot; Tequila tends to be the one constantly reminding you that you need to hurry up and get your ass to the place you do not in fact have to hurry up and get your ass to. This leads to a bit of Hypocritical Humor later on, when Tequila joins you and Katya takes over as Mission Control. Tequila complains about Katya always interrupting with mission objectives, after spending a couple levels doing nothing except interrupting you with mission objectives. Continuity Nod: Both Weyland and Yutani appear in the modern-day settings, establishing the company (and the Xenomorph-chasing hysteria) for the earlier movies. Continuity Snarl: The Alien vs. Predator films would appear to compatible with the Shared Universe of the Alien vs Predator video games, novels, and comics until Prometheus and Alien: Covenant established a new origin for the Xenomorphs. In The Predator, the tail spear from Alien vs. Predator is shown in a display case, implying Alien vs. Predator is still canon to the Predator half of the franchise, while assuming The Predator is still canon to the Predator franchise. Corrupt Corporate Executive: Anyone high up in WY is guaranteed to be doing something dangerous, unethical and in all likelihood stupid involving the nearest Hive and/or ancient ruins. It's apparently true for the whole corporation: Weyland-Yutani's contract has a clause that allows them to feed you to a Xenomorph just to see what happens when they feed you to a Xenomorph. Cool Versus Awesome: The whole point of pitting Aliens against Predators. Crippling Overspecialization: How the Predator is balanced against the Marines and Aliens in the games. As ridiculous as their gear is, catch one holding the wrong tool for the job and you've got a much better chance at winning. Most evident in the second PC game, especially in multiplayer where the three species could be further divided into classes and no single Predator would have access to a weapon for every situation. Also, Praetorian Aliens. Yes, they hit hard and can take quite a bit more damage than regular Aliens... but they can't pounce or climb walls. Very bad trade off... Happens with the most marine and some predator units in the RTS. Very good at fighting 1 type of unit. Terrible at dealing with pretty much anything else. Crossover: The entire point of the series in a nutshell. Interestingly enough, Mortal Kombat X contains a Xenomorph and Predator as guest characters, making that game an extension of the AVP brand. Aside from the MK series, it also marks a crossover with Friday the 13th and The Texas Chainsaw Massacre thanks to the appearance of Jason and Leatherface. Dark Action Girl: Dunya in the second PC game. She's even the main playable human character in the Primal Hunt expansion pack. Decapitation Required: The only way to finally kill Big Bad Karl Bishop Weyland is with a headshot, since in the final quickdraw duel he completely ignores being shot anywhere else. Deadly Lunge: In the original PC game, Aliens simply had the best jumping ability; which could clear the distance between them and opponents quick. In the sequel, the Alien's pounce ability was now an actual attack. In the newer game, it's possible (if awkward control-wise) for the Alien to run, leap and attack, but it's not a specific move. Both the Alien and Predator have a ranged lunge move in the 2010 game. The Runner alien in the RTS has such an attack. Can be upgraded to inject the target with toxic spores on impact, fun. Denser and Wackier: Some of the AvP comics got pretty weird. Deadliest of the Species, in particular, featured such elements as rogue holographic AIs, hybrid Alien/Predator/Humans capable of moral choices, identity crises with humans reformed into "trophy wives," genetic animosity between Aliens and Predators, and Alien influence able to grant people superpowers. Difficult, but Awesome: The Aliens take on this role in the 2010 game's multiplayer. You're more fragile than the Predators and the Humans, you move differently, and your only attacks are melee-oriented, but a skilled player can make use of their prodigious speed, wall-crawling abilities, and swift takedown maneuvers and become a absolute nightmare to play against. Actually, Aliens have more health than marines. Marines have 100 health, Aliens 130 and Predators 150. That doesn't diminish the above point, though; since the Aliens make growling noises when moving at speed, they can subvert their own attempts at stealth. It makes both stalking prey and engaging in combat inherently risky, but still intensely rewarding. Nothing like getting an execution finisher on a Predator. Disposable Vagrant: In AvP 2. Downer Ending: The 2010 game ends with the player marine and a xenomorph-infected squadmate being "rescued" by a dropship... crewed by Weyland-Yutani mooks, who are having a nice chat with Karl Bishop Weyland about how now they know where the Xenomorph homeworld is. Dragon Their Feet: In the 2010 game, Praetorians, supposedly there to protect the Queen, don't even begin to show up until well after she's killed. 11th-Hour Superpower/Game-Breaker: In the Predator campaign of the 2010 campaign, the combistick spear, which doesn't become available until the second-to-last level. It can be thrown several dozen feet, is a one-hit-kill against almost everything, and best of all doesn't drop you out of cloak. Once you get it, you can waltz through human enemies without any effort, and even aliens become much easier to handle. Also, during the last boss fight, your energy automatically recharges, which suddenly makes the mines and plasma caster much more attractive options than they were previously. In AvP2, the Marine gets two. The last level starts with Harrison in Alice, the squad's military-grade powerloader with a bunch of guns and lasers and rockets and stuff strapped to it. He looses this, but after defeating the Queen, gets the sniper rifle to hold off the Praetorians while the squad evacs. The sniper rifle does crazy stupid damage, even if you aren't all that accurate with it, basically one-shotting the Praetorians. Elite Mooks: The second PC game has Dr. Eisenberg's personal cadre of illegal Combat Synths; bald, muscular androids with reinforced bodies and several times as much health as standard human troops. They can see in the dark and even right through the Predator's cloaking device, and some of them carry miniguns and rocket launchers. A good headshot still decapitates them, though. Combat Synths, now referred to as Combat Androids, make a return in the 2010 AvP game during the later levels in all 3 campaigns. They normally carry either a shotgun or, more likely, a sniper rifle. They can take about 25% more damage than a human Marine (Weyland's black-uniformed personal Praetorian Guard are even tougher, and can take at least 60 rounds from the pulse rifle to kill), and headshots do not help. Technically, the player alien as well; the Marine and Predator players slaughter your sisters by the dozens, however, you typically manage to go through an entire army of marines, with one or two predators also on your hit list. Much the same is true of the player alien, who hasn't ever fought aliens before. Praetorians and Predaliens in the FPS and RTS. Survival Mode in AvP 2010 has mini-Praetorians in the later stages; they behave like regular aliens, but have Praetorian headcrests and enhanced health (it takes up to 5 close range shotgun blasts to kill one, although alternatively it "only" takes a few dozen bullets to do the job). Emergency Weapon: In the second game, you had a knife if you ran out of ammo for all your guns. Given the nature of the enemies you faced, though, if it ever came down to that you were pretty much screwed anyway. The 2010 game gives you a pistol with infinite ammo, but it takes almost a full 18 round mag to kill a single Alien drone. Medics and basic Synthetics in the RTS have pistols. They work as well as you'd imagine. Enemy Mine: A staple of the series - it's happened in the original comics (where the elder Predator and humans form a strained bond), Deadliest of the Species, the first movie (which has the last surviving human and the last surviving Predator teaming up to fight the Aliens) and the Capcom game (where the Predators team up with two Cyborgs to fight the Xenomorphs). Evil Versus Oblivion: Nearly every title under the AVP umbrella falls back to this trope eventually. The Predators are not nice people, but they are still people whereas the Xenomorphs are a threat to the survival of everything else in the universe. Excuse Plot: All of the games by Rebellion (the Jaguar, the 1999 PC game, and the 2010 game) have only a bare-bones outline cribbed from the films for the plot, as the games are much more about atmosphere than story and most players know everything they need to know about what's going on from the films. Alien Vs Predator 2 by Monolith has a much more developed and coherent plot, though it takes playing through all three different species campaigns to get the full picture of it. Face Full of Alien Wing-Wong: Especially in the 2nd game Fake Difficulty: In the 2010 game, the Marines don't have any sort of alert to tell them from what direction they just took damage from. In theory the motion-capture device should tell you, but Aliens don't move when they are beating you up. Alien vs Predator 2, and it's expansion Primal Hunt in particular, is chock-full of invisible triggers that will spawn a xenomorph horde pretty much within melee range the moment you cross them, making your motion tracker all but useless. Final Solution: Rykov's ultimate goal is to wipe out the Predators with a Synthetic Plague. At first, he seems motivated by revenge for his own past experiences with them, but the research logs show that he's legitimately disturbed by what his discoveries say about their culture; whether sparing other species the fate of being hunted is part of his motivation or just an excuse for his revenge is left ambiguous. Finishing Move: The aliens and Predators. The humans just have to make do with smacking enemies onto their backs and shooting them. Firing One-Handed: Schaffer fires any gun he picks up one-handed. Using his natural arm. Even the Smartgun. He is (an Expy of/descended from?) an Arnold Schwarzenegger character. Fragile Speedster: The player aliens in the PC games are not too durable, but are exceptionally fast, and due to their wall-crawling, far more mobile than the other species. It's toned down somewhat in the sequel, where it's possi