Although there are loads of different sci-fi sub-genres out there (eg: cyberpunk, biopunk, sci-fi horror, dystopic sci-fi, space opera etc…), most sci-fi stories can basically be divided into two different categories – stories involving aliens and stories without aliens.
This might seem like a trivial difference – after all, sci-fi is still sci-fi regardless of whether it contains aliens. But whether or not aliens are involved can vastly change the entire atmosphere, tone and style of your sci-fi story in ways that you might not expect.
Since there is no real “right” or “wrong” answer to this question, I’ll explain some of the ways that deciding whether or not to include aliens in your story can affect your story and leave you to draw your own conclusions.
So why does this make such a difference? Because the focus of the story is completely different.
In a sci-fi story where humans are the only intelligent life in the universe, the focus of the story is firmly on man-made technology and human society. In other words, your sci-fi story is like any other kind of “realistic” story, with the only difference being that it is set in the future rather than in the present or the past.
In addition to this, deciding not to include aliens in your sci-fi story also carries the implication that humans are alone in the universe – which can either make your characters more resourceful (eg: no aliens are going to rescue them if they get lost in space), can add a nihilistic existential gloom to your story (since we’re literally totally alone) or it can make your readers feel slightly better about being human (because we’re the most awesome lifeform in the universe).
These types of sci-fi story are also one of the easiest types of sci-fi stories to write, for the simple reason that the only really new stuff you have to come up with is new technology for your human characters to use.
However, if you include aliens in your sci-fi story, then the focus on your story will be on humans trying to find their place in a varied universe, interplanetary relations, the unknown and a whole host of other subjects.
Rather than an individualistic story about humanity finding it’s way in an “empty” universe, sci-fi stories involving aliens have more of a focus on community, politics and social relations. I mean, for starters, if we lived in a universe filled with many different alien societies, would our current distinctions between nationalities, religions etc… on Earth matter as much as they do these days?
In addition to this, alien characters can be used as a metaphor for various parts of human society (eg: the fervently capitalist Ferengi characters in “Star Trek: Deep Space Nine”). Alien characters can also be used to incorporate more fanatistical elements into your sci-fi story too (eg: telepathy, pyrokinesis etc..) and alien worlds provide a lot more variety to the settings of your story too.
However, coming up with an interesting new alien species can be fairly difficult. Yes, you can just invent them using your imagination (and this is a fairly common way of creating alien characters) – but, if you want your story to appear more “realistic”, then you need to consider all sorts of other things too (eg: how your alien characters evolved etc…).
Of course, there’s also something of a middle ground between these two options. For example, you can have a mostly human-based sci-fi story which also hints at the existence of aliens too (eg: like in a TV show like “The X-Files”) or you could do the complete opposite and have a mostly alien-based story that features a few human characters (eg: like in a TV show called “Farscape”).
As I said earlier, there are no “right” or “wrong” answers when it comes to deciding whether to include aliens in your sci-fi story. But, I hope that this was useful 🙂