Soft Science and Hard Science

There are many different types of stories about aliens. In some, an alien species looks like humans with pointy ears; in others, an alien might be a sentient computer program or something that doesn't follow Earth's biological laws. While it's only slightly less difficult to talk about "realistic" aliens than "realistic" magic, there are different levels of "realism" that an alien might have.

## Physical Bodies

The first way of classing aliens by realism is by how they behave physically: what they look like, how their bodies work, and what they can do.

### Rubber Forehead

A "Rubber Forehead" alien appears to be a human being made up to look alien: green skin, pointy ears, plastic prosthetics. If the aliens are biologically different from humanity, the differences are well within the range of terrestrial life: using hemocyanin for oxygen transport, claws rather than hands, different arrangement of vital organs. Whether because of difficulty in creating sufficiently strange aliens or to deliberately echo "Yellow Peril in Space" aesthetics, this tends to be one of the more common television and film portrayals. Common "justifications" for the similarity are convergent evolution (a humanoid body plan being more efficient in a variety of situations) or a precursor race (a humanoid species that deliberately engineered intelligent life to look like themselves).

### Starfish

A "Starfish" alien is very much nonhumanoid, but uses similar biochemistry to Earth life. They might resemble nonhuman Earth life (such as octopi, slime molds, or... well... starfish) or might be completely different from anything on Earth. Starfish aliens can survive on Earth, but cannot pass for human.

### Strange Sphere

A "Strange Sphere" alien is incredibly different from humans. Its biochemistry is wildly variant, being based on ammonia or silicon or methane or cyanide or something else that tends not to be frequently used by Earth life. That is, if it *has* biochemistry in any conventional sense; a Strange Sphere alien might be made of sound, or a localized self-sustaining electrical disturbance, or an intelligent shade of the color blue. Particularly strange aliens, especially those summoned by a witch's Paradox manifestation, might even rely on alternative laws of physics. In all cases, a Strange Sphere alien requires special equipment or powers to survive on Earth.

### Trans-Xenic

A particular note should be made of "Trans-Xenic" aliens. These are the alien equivalent of transhumans: beings that have deliberately altered themselves in order to enhance their own capabilities. A Trans-Xenic alien might be a substrate-independent mind, existing as a ghost or as a machine or as computer data. It might alter itself to survive on Earth, taking on terrestrial biochemistry or even human guise.

## Mental Variations

Another classification for aliens is their mindsets: how they think, how they behave, and how they process information.

### Basically Human

This type of alien is more or less a human being with an unusual body and possibly a cultural background based on no human culture. A Basically Human alien thinks along human lines, modified by any nonhuman beliefs he has. This is probably the easiest type of alien for the Storyteller to run, since she doesn't need to pretend to be another species; but it is also the hardest to sell as convincingly *alien*.

### Human Plus And Minus

A Human Plus And Minus alien is based on human behavior, but its mental processes are slightly different in ways that go beyond what can be explained purely by culture. A Human Plus And Minus alien might focus on unusual senses, approach problems in unusual (but no less effective) ways, or have a few incomprehensible motivations (and have trouble understanding certain human motivations); but is otherwise like a human being and can convincingly imitate human behavior.

### Inhuman

An Inhuman alien has thought processes completely different from anything on Earth. It likely struggles with things that are obvious to a human being, but at the same time can make cognitive leaps that are impressive (or even sanity-shattering) to a human being. The way it thinks is not even close to human, and keeping up with it is a challenge for any player. This is probably the most difficult type of alien for any Storyteller to portray convincingly: even a character more intelligent than the Storyteller can be simulated by using various methods (such as reversal points; see *Mage: The Awakening: Imperial Mysteries*, page 17), but an Inhuman alien should come across as having human intelligence, but a nonhuman mindset.

### Variable Intelligence

All of this, of course, presupposes that the alien is of generally human or human-like intelligence, in terms of cognitive ability if not mindset. An alien could well have sub-human or super-human intelligence; the alien might be a cosmic intellect or the equivalent of an animal.

## Technological Base

One final classification is what kinds of technology the aliens use.

### Generation Plus Two

The simplest way is to base alien tech on human standards. Alien technologies are essentially human tech with a few hundred more years of advancement, or "what today's scientists think we'll have in a hundred years": fusion engines, Alcubierre drives, and nanofabricators.

### A Copper Plated Chunk of some 1980s Junk...

Another fairly straightforward method is to give aliens tech that followed a different development path. A species that developed on an ice planet was never able to master fire, so their devices for the most part use increasing complexity or redundancy rather than improved materials. A methane-based species communicates by chemical signals, so their technology was always more chemically-oriented than humanity's.

### Things Man was Not Meant to Know

With an Inhuman alien, there's another option. An Inhuman alien's thought processes are not at all similar to a human being's, which means that it has different cognitive blind spots. Different mindsets, naturally, lead to different priorities; but they could also lead to an alien species exploring sciences that humanity did not (or could not) consider: technologies based on fractional-dimensional mathematics, empirical symbolism, or things that no human can describe in words.

### Sufficiently Advanced

Of course, another thing you could do is to make your aliens psychic or magical. It's not exactly "hard" science fiction, but that was kind of not an option once you started playing a game about FBI psychics and scions of Hell fighting Nazi Dracula. And besides, there's always Clarke's Third Law; an alien species might be advanced enough to do a decent impression of a deity.

## Motivations

So what motivates the aliens? What are they trying to do? Different answers have different amounts of "realism" to them.

### Mars Needs Women

One of the most stereotypical (and least realistic) possibilities is that the aliens are seeking breeding stock. The aliens are kidnapping humans and using them as reproductive slaves, or in a slightly more realistic take incorporating human genetic material into their own DNA. This really only works with Rubber Forehead aliens, and even then is not terribly sensible; any alien is going to be a different species from humans, and the usual explanation (that humans are somehow the most attractive species in the universe) makes little sense given that any species is going to have its own standards of attractiveness. Still, it makes for a classic if rather cheesy science fiction game.

### To Serve Man

Another common (and unrealistic) motivation is that the aliens want to eat humans. With Strange Sphere aliens, this obviously doesn't make sense (since any kind of Earthly life is going to be pure poison to anything with even mirror chemistry, let alone silicon chemistry). With other aliens, it makes more sense, but still not much, given that humans are better-able to defend themselves than most Earth life, mostly bone, and expensive to raise; but this might be part of the appeal: an alien species might feed on mental energy or be seeking a luxury good. In any case, putting humanity in the middle of the food chain is a standard source of horror (see everything from vampires to Polyphemus).

### Alien Slavers

In a lot of fiction, aliens try to enslave humans. For reasons listed in a Project Heimdall essay (see Further Reading), this doesn't work for Strange Sphere aliens, and is of limited realism for any other type; given the inefficiency (among various other practical and moral problems) of slave labor, any alien species able to reach Earth would likely be able to automate whatever tasks they needed humans to do. But if you need a semi-realistic reason for aliens to invade, this works.

### You Will Be Assimilated

Humans have mental blocks that aliens don't: concepts that the human brain can't parse, or mental processes that create certain blind spots. But it goes both ways: there's thoughts humans can have than aliens can't. Different mindsets could well lead to different discoveries; even a galactic empire might have missed a few things on their way to inventing stardrives. In this scenario, aliens intend to harness the thought patterns or unique biological traits of other species, uncovering wonders unthinkable to both groups.

### Panning for Neodymium

Many conquests on Earth were driven by a greed for resources: living space, arable land, gold. So too is it with aliens; the aliens hunger for some resource on Earth. Of course, there's plenty of most resources in places that aren't defended by a species with nuclear power; metals in asteroids, water and simple organic compounds in comets, hydrogen and helium-3 in gas giants, living space out in planetary orbit, and so on. But perhaps there's something on Earth that aliens can't get anywhere else; complex organics such as cacao or petroleum, or substances not known to human science such as orichalcum or ectoplasm.

### Zookeepers of Gor

Life around the Universe is wonderfully diverse. Here, there are the monkey-men of Earth. There, the tentacled horrors of Xilgax V. And over there, the spore-colonies of Tileax. All brought from their native worlds for the edification of the youth. No reason to feel guilty; in many cases, these are the only surviving examples of the species. And even when they aren't, the specimens are provided with all their needs and every comfort they could want. That infighting over in the Human exhibit? That's perfectly natural; just animals acting like animals.

### The Little Green Man's Burden

In many of Earth's conquests, the conquerers were convinced that they were doing the right thing. God demanded that they spread his Word to the infidel, so they brought it at swordpoint; better to be tortured into a conversion than to burn in Hell. Their civilization was obviously technologically superior, so they had a duty to bring the fruits of their superior culture; Western culture was obviously *better* than their primitive ways. Kill the Indian to save the Man. Breed the Black out of the savages. And it wouldn't be difficult for aliens to justify themselves similarly; isn't a society that can cross interstellar distances obviously more advanced than one that can't? Doesn't it have a right, nay a duty, to spread the light of Reason?

### Preemptive Self Defense

Humanity is dangerous. A species that discovered nuclear power and spaceflight before it stopped squabbling over petty differences in location and color. A species that nearly blew apart its planet over a question of economics. A species that seems driven to fight and conquer, for no reason beyond battle and conquest itself. A species that insists on allowing deadly inequalities to persist despite easily having the ability to correct them. A species short-sighted enough to deny its planet is warming even as its lower lands become uninhabitable. While some projections say that they will eliminate themselves or evolve into a more stable form within a thousand years, what if they don't? What if they manage to leave their solar system? What if they start a war (which they seem to be frighteningly good at) with us? What if they bring their short-sightedness to Galactic politics, and doom us all? Best to try re-engineering them into something sensible, and if that doesn't work a rock at 1% the speed of light ought to solve things.

### Unknown Unknowns

And then there's all the various reasons hostile aliens could have that a human couldn't predict. An alien might be driven by instinct to destroy all other life. An alien might have an irrational hatred of Earth. Aliens are, after all, alien, and an Inhuman alien might have any number of reasons. Even more or less human aliens might have their own reasons a human being could not predict: perhaps a fugitive has landed on Earth, and the government of the fugitive's new home nation is refusing to extradite. Maybe Earth was an archaeological site until a bunch of monkeys started tampering with it. It might even be that Earth is far more important than it seems: maybe it really *is* the center of the Universe.

## Further Reading

* TVTropes - Most Writers Are Human
* TVTropes - How to Invade an Alien Planet
* SCP Foundation - Project Heimdall
* Aliens Guide to the Conquest of Humanity