Here are 30 sci fi writing prompts covering space, near-future technology, first contact and time travel. Each one starts with a single 'what if' and a human consequence, because the best science fiction is less about the gadget than about what it does to people, and each is sized to fit a short story of under 7,500 words.
Science fiction lets you ask the questions the real world isn't ready to answer yet. What happens when memories can be edited? Who gets the last seat on the colony ship? But it's easy to get lost in the world-building and forget the story. These prompts keep one foot on the ground: a single big idea and a character who has to live with it. Pick one and you'll have a plot, not just a premise, and a character readers will care about when the big idea starts to bite.
Sizing your sci fi story
Most science fiction markets and awards use the same length categories, set out in the SFWA's Nebula rules. Knowing them helps you plan: a premise that needs a whole society explained probably isn't a short story. It's also worth remembering Edgar Allan Poe's advice from The Philosophy of Composition, that a story read in a single sitting, with its ending decided first, has the strongest unity of effect.
| Category | Length | Sci fi that fits |
|---|---|---|
| Short story | Fewer than 7,500 words | One invention, one character, one consequence |
| Novelette | 7,500 to under 17,500 words | A small crew facing a crisis |
| Novella | 17,500 to under 40,000 words | A colony, a mission or a city under change |
| Novel | 40,000 words or more | Whole societies, several viewpoints |
Space and exploration prompts
Isolation, distance and limited resources create pressure fast. Keep the crew small.
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The first crew to land on a distant moon finds footprints that match their own boots.
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A generation ship's captain discovers the destination planet was ruled uninhabitable decades ago, and the crew were never told.
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An astronaut on a long solo mission starts receiving letters from Earth written by someone who died before launch.
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A mining crew on an asteroid strike something that isn't rock.
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The colony's oxygen farm is failing, and only one person knows it's sabotage.
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Two rival space stations must share their last shuttle to escape a solar storm.
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A child born on Mars visits Earth for the first time and hates it.
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Mission control loses contact with a probe for a year. When it returns, it has company.
Near-future technology prompts
Take one technology that already exists and push it a step further. Ask who benefits and who loses.
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A memory-editing clinic offers to remove your worst day. You find out you've already been a customer.
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Every citizen has a public trust score, and yours drops overnight for no reason you can find.
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A grief app recreates loved ones from their messages. Your mother's version starts saying things she never would.
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Self-driving cars are perfectly safe, until one refuses to let its passenger out.
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Smart homes start sharing information with each other about their owners.
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Teenagers can switch off their emotions with an implant. One girl refuses to have hers fitted.
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A city replaces all its streetlights with sensors that predict crime. The sensors keep flagging the mayor.
First contact prompts
The aliens are rarely the most interesting part. Focus on how humans react.
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Aliens arrive and ask to speak to Earth's best storyteller.
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I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
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First contact is made by a nine-year-old with a radio set, and the aliens only trust her.
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An alien signal turns out to be a warning, sent a thousand years too late.
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The visitors are friendly, polite and staying, and they've brought their own laws.
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A translator realises the aliens' language has no word for lying.
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Humans are the aliens, landing on a planet whose people have been expecting them for centuries.
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The alien ambassador falls ill, and only a small-town vet is close enough to help.
Time travel prompts
Decide your rules first: can the past be changed, and what does it take from the traveller?
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You can travel back in time, but only to moments you've already lived.
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A time traveller keeps visiting the same café on the same day, trying to stop one conversation.
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Letters from your future self arrive weekly. This week's just says 'Don't.'
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A museum of the future displays an object you own today, labelled as the cause of a disaster.
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Time tourists visit your town every year on the same date. Nobody local knows why.
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A scientist sends a message back one minute in time. The reply comes from someone else.
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You wake up a day earlier every morning.
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A historian travels back to witness a famous speech and accidentally gives it.
How to get better science fiction
- Change one thing about the world, then follow the consequences honestly.
- Give the technology a human consequence. Every invention creates winners and losers.
- Explain less than you think. Readers will fill gaps if the characters behave as if the world is normal.
- Decide the ending first, as Poe advised, and plant the clue that makes it inevitable.
- Check your length against the Nebula categories before you submit anywhere.
When your story's ready, my directory of websites that publish fiction lists markets to try, and my guide to SEO copywriting explains how to help readers find an author site.
My advice for sci fi writers
Start with a near-future prompt, because the technology is close enough to feel real and the human questions write themselves. Keep it under seven and a half thousand words so it counts as a short story, and test the ending on a friend. If they say 'that's terrifying, because it could happen', you've written good science fiction. If they say 'I didn't understand the ending', cut some of the explanation and add one clue earlier.
Frequently asked questions
What is a good sci fi writing prompt?
One with a single big 'what if' and a human consequence, such as a memory-editing clinic where you discover you've already been a customer.
How long is a science fiction short story?
The SFWA's Nebula rules define a short story as fewer than 7,500 words and a novelette as 7,500 to under 17,500 words.
What are the main types of science fiction?
Common types include space exploration, near-future technology, first contact, time travel, dystopia and post-apocalyptic stories.
How much should I explain the science?
Less than you think. Let characters treat the world as normal and give readers only what they need to follow the story.
How do I write a time travel story without plot holes?
Decide your rules first, such as whether the past can be changed, and stick to them throughout.
