Hostile Terraforming

Imagine you are a leader of an alien race currently at war with another race, and your natural habitats are drastically different. How would you perform a hostile takeover of a planet?

By making it so the planet is now inhabitable by you and not by the natives, of course! Converting the atmosphere, reshape the land and sea, overrun the native ecosystem with one more suitable - whatever is necessary to make the very ground your enemies tread on no longer their ally.

A specific context for Terraforming, and if it's an Earth-like world being changed for to another ecosphere, the term would be "xenoforming". Depending on methodology, it can involve Grey Goo, Gaia's Vengeance, or Meat Moss. Due to the destruction, this is a Class 4-5 Apocalypse How, depending on how much of the planet's multicellular life is replaced.

Examples of Hostile Terraforming include:

Comics

• In the first season finale of the Twelfth Doctor in Titan's Doctor Who comics, the Hyperions scorch the surface of the Earth to create an environment suited to them. To be clear, this was not their plan. It's just a side effect while they build a Star-Killing doomsday device.
• The first issue of Sillage/Wake involves an alien who intends to terraform a jungle planet to suit his species, although in this case he's unaware that there's one sentient being (the human girl Navis) and lots of semi-sentient animals already living there.
• Transformers:
  • In Transformers Generation 2, the Cybertronian Empire's modus operandi was to kill all the inhabitants of each planet and then mechaform the planet itself to make replicas of Cybertron. By the time the series began, they'd done this at least seventeen times.
  • As Regeneration One points out, in a bit of Black Comedy, the hostile part of this trope depends entirely on how you define "life."
  • Transformers Robots in Disguise reveals that Devisiun was once a Sugar Bowl before the Cybertronian colonists arrived and squashed out the organic biosphere. Made even worse because Eukaris shows that Cybertronians don't have to do this to make a colony successful.
  • A "The Bad Guy Wins" AU of the first film featured Megatron using the AllSpark for this. As many pointed out, he was in a perfect position to go back to Cybertron and use the AllSpark to restore the planet but since Evil Is Petty, he couldn't resist doing this first.

Fanfiction

• The since removed All That Remains has Megatron cyberform Earth. Unlike most examples of this trope, he's successful.
• The crux of the conflict in The Conversion Bureau and its various spinoffs as the Equestrian barrier is turning Earth into Equestria.

Film

• The Arrival. Aliens are causing global warming in order to kill off humans and make the planet more comfortable for their kind.
• Battle for Terra - The humans sends a machine that can convert the air on Terra to be human breathable in seven days. This would leave the air unbreathable for the Terrians.
• In ancillary media for The Force Awakens, it's said that there was life on Ilum but the First Order, having learnt from Endor, wiped out all lifeforms before they rebuilt the planet into Starkiller Base.
• Ego the Living Planet mixes this with The Assimilator in Guardians of the Galaxy Vol. 2, using his seeds to try and turn every inhabited planet into an extension of his body by rewriting their biosphere.
• The DC Extended Universe:
  • In the climax of Man of Steel, Zod's forces use a World Engine to try and turn Earth into New Krypton.
  • In Justice League (and Zack Snyder's Justice League), the forces of Apokolips try the same thing with their Mother Boxes.
• The Genesis Device was first featured in Star Trek II: The Wrath of Khan. In Star Trek III: The Search For Spock, the Klingons expressed concern that it would be used for this if turned on their planets. Of course, it would only qualify if the device was in Federation hands. In Klingon hands, it would be a tool for peaceful colonization and expansion.
• The Trollenberg Terror is about aliens' native air slowly enveloping a mountain and later the surrounding area.
• They Live used a similar premise, with aliens "turning our world into theirs."

Literature

• In The War of the Worlds, the Martians use areoforming as a weapon, and plant the Red Weed wherever they find room for it. Possibly an Ur Example.
• Last and First Men, the Fifth Men escape a dying earth by terraforming Venus. Halfway through the process they discover that Venus is inhabited and oxygen is lethal to the natives, they keep at it anyways.
• War Against the Chtorr features this prominently.
• A specialty of the Yuuzhan Vong in the New Jedi Order.
• This is the long-term plan of the alien invaders in The Tripods series.

Live Action TV

• In Quatermass II an alien vanguard takes over selected humans so they can build a chemical plant to make an atmosphere that will support their kind of life, and kill off all terrestrial life.
• The Star Trek: The Next Generation episode "Home Soil" featured a Federation terraforming project that was doing this by accident.
• Star Trek Deep Space Nine: Sisko used a specialized warhead to poison the atmosphere in such a manner that it would be uninhabitable for human life, but functional for Cardassian in an attempt to force Eddington to surrender. Though the Maquis did pretty much the same thing (except rendering it uninhabitable to Cardassian life but safe to human) to multiple Cardassian colonies.
• In the Stargate SG-1 episode, "Scorched Earth", an alien vessel was terraforming a planet inhabited by Human Aliens into something hostile to their form of life. Unlike most of the civilizations SG-1 encounters, the aliens need a very specific environment to survive, meaning they can't easily be moved to another world. Eventually it's resolved when it turns out the terraforming ship has information about said aliens' home planet.
• Doctor Who:
  • In "The Seeds of Death," the Ice Warriors attempt to extract the oxygen out of Earth's atmosphere and covert it into a world more suited for them.
  • In "The Mutants," an expensive, imperial, empire invades a planet and attempts to terraform at the cost of all indigenous life. Oh and the imperials are humans.
  • In "Terror of the Zygons," the Zygons try and modify Earth's climate to emulate that of their destroyed homeworld.
  • "The Sontaran Strategem/The Poison Sky," weakened by their eternal war with another race of Scary Dogmatic Aliens, the Sontarans hatched an uncharacteristically circuitous plan to bathe the Earth in gas which is poisonous to native life but nutritious to themselves, so that they can use it to spawn more soldiers.
• The Andromeda episode "Point of the Spear", the Pyreans (aliens that live in Venus-like environments) tried to forcibly pyroform a Commonwealth world. A large battle breaks out, and to prove that the Commonwealth is not one to be messed with, Dylan orders the planet's destruction via Nova Bomb.
• One episode of the new The Outer Limits had this with a new model of car that would poison the atmosphere for infiltrated aliens.
• In the Season 3 finale of Supergirl, the Kryptonian Witches have Reign try to turn Earth into New Krypton. Just Reign. As in she pounds Earth's insides to reshape it into Krypton.

Manga and Anime

• Lord Slug wanted to freeze the Earth because of this in the fourth Dragonball Z movie. "De Terraforming" was discussed in the Dragon Ball Abridged movie version.

Tabletop Games

• Metagaming's MicroGame 12 Invasion of the Air-Eaters. An alien race invades and uses Atmosphere Converters to change Earth's air to sulfur dioxide, which they can breathe it but we can't.
• In Warhammer 40000, "tyrantforming" is the first stage of devouring a planet by the Tyranids - the spores dropped onto the surface merge with local plantlife, turning it into Hungry Jungle - rapidly draining the ground of all nutrients. The Tyranids then devour the plants.
  • Orks are described as "an invasive ecosystem by themselves", and shed spores to generate new creatures, which will grow to be squigs, grots, gretchen or full orks depending on the conditions. With enough orks, they create their own flora and fauna, and the whole ecosystem is "orkoformed".

Video Games

• The Command and Conquer Tiberium series centres around humanity adjustments to a world being transformed by the eponymous Technicolour Crystaltech - which not only convert the atmosphere and the ecosystem, but also extract useful minerals from the Earth's crust for easy harvesting when the invaders finally arrive in person.
• Half-Life 2 in its released form contains hints of this - most notably, the Combine drain the Earth's oceans and use Xen species such as Headcrabs and Leeches as biological weapons. The original beta however went much further - a key location in the game was the "Air Exchange", which replaced the air with noxious gases breathable by the Combine, and which meant that all human characters in the game had to wear gas masks.
• In Star Control II, Mycon Deep Children reshape planets they collide with, stimulating their volcanic activity to the point where it's comfortable for Mycons - obviously, since they enjoy temperatures above 600 Kelvins, it's less than comfortable for pretty much everyone else. Mycons don't seem to care.
• In Spore, you can deterraform planets of an enemy empire to reduce the level of colony that planet can maintain (especially effective against enemy home-worlds, as it reduces them from thriving T-3s with extra settlements, to a basic T-2 with two settlements at best). Empires will regard this as an act of war. More in line with this trope, the Grox, Enemy to All Living Things, can be killed by terraforming their planets.
• Phazon from the Metroid Prime subseries tends to do this. It turns out to be Sentient Phlebotinum that originates from the planet Phaze, which deliberatly seeds the universe with phazon meteors.
• The Korath Clan in Galactic Civilizations 2 prefer to eliminate a planet's entire biosphere. They can then colonize the resulted toxic world.
• All K-D Labs RTS games employ combat terraforming to some extent. All sides in Perimeter and two sides in Maelstrom can terraform the battlefield to create passages and so on. Both sides in Perimeter 2 (Exosus being waterborn, Comeback being landlubbers) and Hai-Genti in Maelstrom instead make parts of land inhabitable only for themselves.
• In Lost Planet: Extreme Condition NEVEC is planning to terraform E.D.N. III in a way that would instantly thaw out the planet and kill the native Akrids and the rebelling colonists. Fortunately Wayne discovers an alternative that won't fry the colonists and by Lost Planet 2, ten years later, most of the frozen wastes of E.D.N. III have been replaced by deserts and jungles, and several new Akrid species are coming out of hibernation.
• In Stars! Claim Adjuster trait can undo enemy terraforming via Retro Bombs. Claim Adjuster races also can use Orbital Adjuster on a planet without conquering it, and Packet Physics races terraform planets they bombard with mineral packets. If environmental requirements of the sides are different (frequently, as it's 3 independent values), it's deterraforming for the target.
• In Haegemonia: The Solon Legacy, high-level spies can reverse-terraform enemy planets. It's not permanent (the enemy can simply terraform it back if they have the tech) but as planet quality is the primary factor in maximum planet population, killing off a few hundred million colonists or at least inciting revolution due to massive overpopulation with a single spy can really wreck someone's day.

Web Comic

• White Noise had this happen in the backstory. The aliens who killed off everyone on Earth's surface then attempted to terraform the planet to suit them, resulting in a clouds of toxic Murk that roam the surface.

Web Original

• Orions Arm:
  • Happened on occasion due to many early colonists preferring to adapt to new environments rather than terraform, putting them into conflict with later waves who would rather change the planet than themselves. Most notably when the original Martian Tweaks were forced to leave their homeworld when the atmospheric pressure and oxygen content were raised to intolerable (for them) levels.
  • A similar thing happened on Venus, despite the extremophile tweaks wiping out the baseline colonists (the former were then banished from the solar system).
  • However, the terraforming of Mars took long enough that a second clade of Martian tweaks emerged, and managed to halt the process at a level they are comfortable at.
  • When Zarathustra, one of the first exosolar colonies, was settled there was minimal terraforming and the tweaked colonists went feral. A couple centuries later Jupiter Transsystems arrived, enslaved the natives, and set up terraforming stations that would have killed off the tweak population if they hadn't also awakened and pissed off the original colony AI.

Western Animation

• Superfriends (1973-74). The inhabitants of the planet Solar Terrarium are moving the Earth closer to the Sun so it will become hotter and more comfortable for them. They are unconcerned that the increased heat and resulting climate change will kill most of the humans living here.
• Transformers:
  • In the G1 cartoon, Megatron tried to use the Key to Vector Sigma to cyberform Earth. When the Key was destroyed, the cyberforming vanished.
  • In the Season 2 finale of Transformers Prime, Megatron turns the Omega Lock against Earth to try and cyberform it into a Cybertronian colony.
    • As some fans realized however, this wouldn't have been hostile per se, as, while it would have killed all humans, it would have also poisoned Unicron making Megatron's plan oddly heroic.
• In Justice League, the Imperiex attempted to do this in the series premier, and for Book Ends, the denizens of Apokolips attempted it in the series finale.
  • Apokolips also tried to do this back in Superman: The Animated Series.
• Oglethorpe and Emory of Aqua Teen Hunger Force tried to do this in the episode "Universal Remonster".
• The Gem Empire of Steven Universe doesn't terraform planets so much as Gem production consumes whole chunks of it leaving the world to be nearly hollowed out.
• In The Avengers: Earth's Mightiest Heroes, Malekith the Accursed tries to freeze Earth to turn in into a climate more suited to the Dark Elves.
• In episode 8 of Ben 10: Omniverse, the Kraaho try to use a fusion engine to superheat Earth and turn its climate into one more hospitable for them. For reference, 100 degrees Fahrenheit, or 38 Celsius, is their equivalent of frigid cold weather.
• The Pupa in Solar Opposites will do this one day, remaking Earth into New Shlorp. Korvo is quite eager to get off the planet, lest the family become part of the recycled matter.

Real Life

• Some scientists worry that terraforming Mars might kill all the native bacteria on that planet since they think that they cannot survive under oxygen atmopsheres.