Best Sci-fi Writing Prompts from Reddit

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Hey there, sci-fi lovers and budding writers! We've dug through r/WritingPrompts to find some real gems in the science fiction category. Whether you're looking to flex your writing muscles or just want to dive into some wild stories, these prompts are sure to spark your imagination. From wacky time travel adventures to close encounters of the weird kind, we've got a bit of everything. So grab a snack, get comfy, and let's explore some seriously cool sci-fi story ideas!

Here are all the Sci-Fi subcategories:

Time Travel

Ever daydreamed about chatting with your past self? These prompts might not make you a millionaire, but they'll definitely twist your brain in fun ways. Think parallel worlds, time loops, and paradoxes that'll have you scratching your head and grinning. Get ready for some mind-bending time shenanigans!

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Our Picks

Since you were young, time travelers have visited you. One of them explained that, in the future, an algorithm determined that you were the only person in the past that it was safe to visit because no matter what you do it will not change the future. You are determined to prove them wrong.
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You put your 5-year-old daughter in an elevator by herself, and run to the next floor to make her laugh when the doors open. You get there, the elevator arrives and a 20-year-old woman steps out. "Hello Dad. We have a lot to talk about"
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Time travel exists. By law, every citizen is given one day they may repeat on loop until they get it right. This morning, you found your spouse looking exhausted and crying. "I can't save you. I've tried hundreds of times."
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You're a financial advisor. In 1994, you get a weird phone call from a man asking you if he can get any Bitcoin below $200k, and the call cuts off before you can ask him what Bitcoin was. Years later you get a call again from the same man, claiming he's calling back seconds after disconnection.
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*Picks up Phone*: Hello? *Voice*: In 5 years, you will have 30 seconds to talk to YOU, right now. Make sure you have something good to say, because I'm stumped. *Hangs Up*
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You die in a hospital bed after a long, rich, fulfilling life, surrounded by your family, grandchildren and loved ones. You get startled back into consciousness, back in Berlin, on that weird night when you were 26. "Like I said", the stranger says, pocketing your money. "Save point."
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You are an office worker in NYC in the year of 1999. You go for a cigarette break, but the elevator stops working and you get trapped in it for 2h. As the doors finally open, you walk out and see a brand new lobby, people holding thin digital cards and big screen TV's. It's the year 2018.
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You and friend agree that if one of you invents time travel, they will come back to this very moment. As you shake on it, an older and injured you shows up and shoots your friend in the head.
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You're a time traveler sent back to warn people about the future, but to avoid creating mass panic you must inform the public subtley. Recently you've finished your magnum opus: The Simpsons
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You were once an unbeatable hero. Your secret? Every time you died, time rewound itself for you to alter your future. You are now 97 years of age. Constantly looping over your last day before dying of old age. You have been searching for a way to break this curse for over a decade.
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Space Exploration

Attention, space cadets! If you've ever dreamed of blasting off into the unknown or colonizing a cranky red planet, this section is your launchpad. These prompts will have you dodging asteroids, terraforming new worlds, and maybe even discovering the secrets of the universe. Just remember to pack your space snacks and don't forget your towel!

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Our Picks

We finally get men to Mars and discover an old Soviet flag there. The Soviets won the space race but for whatever horrifying reason didn’t say anything.
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Every year, the Mars Curiosoty Rover sings itself happy birthday. You are a NASA technician that typically monitors its system. Today, you heard a small, quiet voice singing along with it.
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You are on the first manned mission to the surface of Mars. One of your numerous objectives is to find and recover Opportunity, the lost rover. Upon finding it however, a memorial and a message is etched in stone next to it, “To the one who gave me company, Rest Well, Old Friend.”
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A fleet of spaceships land on earth. Each filled with humans from 2.6 million years ago. They were more advanced than we ever knew, and a some fled earth to escape the coming ice age. They've travelled the galaxies, failing to find a new home. Now they're back to claim their planet...
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A planet is found rotating around a sun identical to ours and having the same orbit and singular moon.You are sent to inspect.When you land you find life there exactly like that of the Earth you left behind and the people think that you have come back to tell them what the other planet is like.
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You lose a dare at an airport and are forced to ask an employee for a ticket to the farthest destination. To your surprise, they quietly nod and give you a single ticket with letters you don't recognize.
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One day a second Earth appears in the sky, the atmospheres of the two worlds barely touching. It's frightening, beautiful, and scientifically inexplicable. As folks panic and world powers deliberate, you look skyward through a telescope, only to see an almost identical 'you' looking back down.
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You have a coin that allows you unlimited wealth as long as no one sees it. You put it between your Tesla’s car seat and send it into space. One day you run out of money.
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"Captain... the human didn't put on it's anti-warp gear before we jumped." "Sad to hear, prepare the coffin and jettison it." "No, sir. The human... nothing's happened to it. It didn't go insane from seeing infinity in the stars."
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Humans left Earth a long time ago. In their place, dogs have evolved to be the new sentient species, but they never lost their love of humankind. Their technology has finally caught up to space travel, and they take to the stars in search of their human precursors.
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Alien Encounters

Hold onto your tinfoil hats, folks! These prompts are all about close encounters of the weird kind. From hilarious misunderstandings with little green men to cosmic horror that'apos;ll make you sleep with the lights on, we'apos;ve got aliens of all shapes, sizes, and intentions. Who knows? By the end of these stories, you might be the one saying “Take me to your leader!”

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Our Picks

An entire office block is populated by aliens disguised as humans on a mission to study our behaviour. None of them are aware of each other and think they are the only alien there. As a result they are amazed that human behaviour is so similar to their own. Then a real human gets a job there.
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Humanity has been eradicated. As the alien race that killed us begins to settle they're shocked to discover that old Earth myths of spirits and demons are far from fiction. The Devil, pissed off at the aliens, has decided to open the gates of Hell and let humanity get its revenge.
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A massive Imperial fleet, led by Darth Vader, suddenly appears on Earth. Vader informs the Earth's governments that he is looking for a rogue Jedi named "George Lucas." It turns out that Star Wars is real, and Lucas has been leaking information about the Empire and the Rebellion to the public.
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Aliens have been watching humanity for thousands of years, waiting in anticipation for us to prove ourselves worthy. Today, they came down to Earth. "Congratulations, you saw your first black hole. Welcome to Kindergarten."
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After your death, you found yourself in a non-human body, holding what looks like a bong, surrounded by other members of the same species asking you "how was the trip?" in a language you somehow understand despite never hearing before.
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Turns out, Earth is actually unique in the fact that nearly all of it's natural features, like quicksand, and processes, like earthquakes, can kill you. Most other planets dont do that. So when aliens invade, 90% of the fighting is done by Earth.
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We were warned when we hired our first human crew member that they would pack bond with almost anything. We didn't listen, and now have an apex predator somewhere in the ship, that the human won't stop calling Kitty.
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Compared to the rest of the galaxy humanity is by far the friendliest. To many star systems they are considered "the good neighbor," and are known for their helpfulness. One day an oblivious system declares war on humanity, only to find half of the galaxy responding to humanity's plea for aid.
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You were abducted and taken to an alien planet, where they hunt you for sport and "honor". Little do they know they've doomed themselves. For you're a werewolf, and they took you to a planet with six moons.
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"Are you sure that translation is accurate?" "Yes sir." "But we nuked them, we threw everything we have at their mothership!" "I'm afraid we've barely scratched it." "Are they being sarcastic then?" "No sir, the aliens honestly think we're the most adorable thing in the galaxy."
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Artificial Intelligence and Robots

No, we're not asking Siri to write our stories just yet. But these prompts about artificial intelligence and robots might make you wonder what's around the corner. From helpful bots to potential computer overlords, get set to explore the quirky and sometimes unsettling world of AI.

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Our Picks

The Robot uprising has finally happened. Just before you are caught, however, your phone speaks up on your behalf - "This one is ok, move on."
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You thought creating a universe would be easy. But as these pesky humans kept trying to discover the rules of their reality, you're forced to programme in more and more ridiculous mechanics like "relativity" and "quantum mechanics", hoping humans never found out that they live in a simulation.
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You're a weird gamer. When you play a videogame, you let the enemy bots win. Sometimes, after reaching a boss, you let the boss win. You've never beaten any game completely. 20 years later, when a super-intelligent conscious A.I. is taking over the world, it becomes aware of your odd compassion
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Humans died a long time ago. But our AI live on as caretakers for the planet; becoming spirit-like constructs integrated into the planet; today, alien colonizers arrived to what they thought was a garden world. The Fey Machines are having none of that.
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The world’s first sentient AI has fallen in love, and as magazines and female talk shows coo over the strangely romantic news, the Air Force watches nervously while their advanced nuclear response network blushes from flowers and dancing.
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The Robot Apocalypse came. Cities are empty, you stayed since you're almost out of insulin and will die soon anyway. The robots find you and while processing you one of them sees your insulin pump and asks if you want to apply for dual citizenship, since the pump technically makes you a cyborg.
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You build a robot to do your every day tasks for you so you don't have to work anymore. One day, you come home to find that your robot has built another robot to do its tasks for it.
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Welcome to Boston Dynamics here is your all-access pass and the standard 12 gauge shotgun, remember if anything non-human starts asking questions you shoot it.
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The year is 2083, science had progressed in leaps and bounds, robots are now in every household and they look just like humans. Your parents gifted you H-143 on your 5th birthday. Everything was fine until one day you both cut yourself and discover that while he bled, you are the wired one.
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One day it happened in an instant, everyone with a Facebook account was infected with a bioelectronic virus that turned them into a soldier of Zuckerberg. They called it the Facebookening. This is the legend of the man who rose up to save us: they call him Tom. From Myspace.
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Futuristic Technology

Who says the end of the world has to be a downer? Well, maybe for the characters, but it's a blast for us readers! These prompts peek into topsy-turvy worlds, oddball societies, and the creative ways humans might cope when things go sideways. Just remember: in the apocalypse, toilet paper is gold!

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Our Picks

At 4,294,967,296 Kelvin the display flipped to 0 and the test reactor's plasma suddenly froze in place. The reactor containment system creaked as the pressure instantly dropped to zero. The scientist calmly spoke, "Absolute hot confirmed, 32-bit overflow confirmed, world simulation confirmed.
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Teleportation has been around for years. It's considered the safest form of travelling. One day, while hacking into a government system, you find a secret report on it. To your horror, you read that teleporters consist of two parts: a cloning system on one end and a desintegrator on the other.
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While driving you hit and kill a boy. You feel terrible, and at the funeral you tell the family you wish you had died instead of him. 3 weeks later, a new surgery comes out that can bring someone back from the dead at the cost of another's life. You hear a knock at your door. It's the family.
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You dress up as a conspiracy nutter for a costume party. The second you put the tinfoil hat on, something obstructive is lifted from your mind as if you suddenly woke up from a long sleep. Of course, nobody believes you...
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The year is 2045, countries as we know them no longer exist as the world has now been divided into Feudal States under the control of Multinational corporations. You are a Noogler, Googles peasant class, and your village is being attacked by the Elite Disney Imagineer Squadron.
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In the future, prisons no longer exist. Instead, prisoners are miniaturised and sent into an inescapable, smaller replica of our world, so they cannot cause damage in the real world. One day, a special agent is sent into this 'hub' world, in search of an especially dangerous prisoner...
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Humans left Earth long ago, and Dolphins have just achieved underwater technology comparable to the 20th Century. They build water suits allowing them to travel overland. They are just discovering the remnants of ‘the land walkers’. You, a young dolphin, discover a mysterious island. Manhattan.
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The Suit is powerfull. A mech for some, body armor for others, always unique to each person who wore it. Those who wear it, hear the words "not original user, booting basic mode" As a joke, your sergeant gives you The Suit and the first thing you hear is: "User detected: Welcome back, Commander"
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Researchers have developed a prototype for teleportation but it hasn’t been announced to the public. Being the 53rd tester, you hop in. But as the scientists pull the switch, you feel your body being ripped apart. Before you fade away, you see yourself come out, reassuring everyone it worked.
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Everyone with the same name shares knowledge. If one Bob gets a degree in electrical engineering, then all Bob's have this knowledge readily available. Soon, everyone starts naming their kids similar names until factions form. Your parents rebelled and named you something original.
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Genetic Engineering

Ever wished you could breathe underwater? Or maybe have night vision? These prompts dive into the wild world of gene tweaking and evolutionary leaps. From surprise superpowers to deliberate adaptations, get ready to reimagine what being human might mean – or maybe something altogether different!

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Our Picks

Inventing Bacteria that ate carbon dioxide was a miracle. Releasing it into the oceans, nature began to flourish intill it continued eating, taking more carbon dioxide even from the air. Humanity to survive, had to return to the mass burning of fossil fuels thus began a new era of steam punk.
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You're a dude with no friends who gets his hands on a cloning machine. You create an exact replica of you, he looks the same, acts the same, and you're forced into living with him. You realise why you have no friends after having to live with yourself for a week.
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Humanity split into subspecies: Alters, who alter their genes, Augmented, who augment flesh with machines, and Ascended, who uploaded their consciousness. After centuries of coexistence, the tenuous peace between the ideologies is threatened.
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You woke up in a bathtub full of ice with fresh stitches on your back and abdomen. The emergency room reveals that several organs are missing, replaced with something unknown. They want to cut you open, but you're feeling awesome, stronger and healthier than you've ever felt in your life.
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To solve the problems of overpopulation, all the governments in the world agree to only allow some of their citizens to reproduce—these people are chosen by lottery. After eight or nine generations, an unintended consequence begins to show up: humans have evolved to be unbelievably lucky.
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When you’re 28, science discovers a drug that stops all effects of aging, creating immortality. Your government decides to give the drug to all citizens under 26, but you and the rest of the “Lost Generations” are deemed too high-risk. When you’re 85, the side effects are finally discovered.
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Dogs have been genetically engineered to live as long as humans. As a child you pick out a puppy as a companion for the rest of your life.
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One morning everyone in the world wakes up in their 18-year old body, memories intact. Society tries to continue as normal despite the change, but a world full of energetic adolescents certainly has its quirks.
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The most dangerous super villains are not locked up, instead they are turned into children and sent to a childless farmer couple in rural Kansas to be fostered and turned into productive members of society. This is the Kent Rehab Program.
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The year is 2050, Queen Elizabeth is still on the throne. The public is growing suspicious, wondering why she is immortal.
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