Defend the Sun Sci-Fi Tabletop RPG Setting

Defend the Sun is a science fiction tabletop role-playing game (TTRPG) setting that launches Space Opera science fantasy into Earth's orbit. Fight invaders, discover frontiers and explore secret alien civilizations eclipsed by our Sun. Adapted for fast-paced modern TTRPGs: the Cypher System, Outgunned, and more.

The alien invaders are coming.

They're coming here. Earth. And our Solar System.

Invaders strike

Bending the laws of physics?

To them: an inconvenience.

To us: a struggle.

They have bigger ships, insidious agents, or endless numbers…

Invaders strike

Wielding superpowers?

To them: born with it.

To us: some assembly required.

So how the hell can we stop them?

The home field advantage.

Alignment of the worlds

Defend our worlds.

8 planets, endless moons.

Living, mysterious biomes.

5 kinds of space techno-magic.

Technology and cosmic power, combined.

The cosmos in your hands.

Quantum shift the odds.

Scorch the earth with Plasma.

But most importantly:

Aliens of our own.

A multitude of local aliens ready to defend our home.

Play as 8 local aliens. Or humans.

Unique powers and abilities.

Hidden, sprawling civilizations.

We Solarians are ready to fight back.

A multitude of local aliens ready to defend our home.

Humanoids with a twist.

Plant. Human. Empathic.

Reptilian. Machine. Chameleonic.

Defend the Sun.

Starships in battle, defenders on land, explorers surveying the alien landscape.

Everything you need for an action-packed sci-fi RPG adventure.

A Familiar Future of Thriving Worlds Threatened by Outsiders.

When humankind first broke through the void of space to land on Neptune's moons, we discovered we were not alone. Naturally, we panicked. But soon enough, we rejoiced because these long-hidden aliens throughout our solar system, our fellow Solarians, were almost just like us. "Good neighbors," we asked, "can we all stop hiding now?"

We heard the answer, and our celebrations ended. "No, the Invaders are coming."


Bizarre aliens from beyond the stars invade our Solar system with alarming, increasing frequency. Some conquer, some destroy, others consume or reshape our worlds, and their arrival is always a harbinger of chaos. Who's to blame? Us. We Solarians chased the siren song of cosmic power, weakening the ancient cloaking devices that have kept our little Solar System safe and hidden from the darkest depths of deep space.

Our Outer Planets contain within their Cores vast reserves of universal energies - the prime cosmic forces of Plasma, Quantum, Dark Energy, Gravity and Void. Our Hypertech mining operations harvest this energy, and now for light-years in all directions we're a giant, shining beacon in the black. On the bright side that means we've got Core forces to power advanced technology, enhanced weaponry and techno-superpowers.

Cosmic powers

What kind of superpowers? If you wield a Core-augmented device, you have the cosmos at your fingertips. You could redirect Plasma to overload your starship's NexusDrive and tear through a pirate blockade, channel Dark Energy to phase through an impenetrable relic vault, evade your pursuers through floating Gravity architecture with your Quantum duplicates, or open up Void portals to dodge a catastrophically awkward conversation.

Or maybe you'd prefer to just bluff your way out of trouble, or shoot anything that moves while you swing your magnetic grappling hook from one spaceship hull to another. Worlds have been saved with a sharp mind and a quick blaster before. It could certainly happen again.

Dimensional-Topographic Image of Node A678-Ɣξ.883.

How do you get around? In our stellar neighborhood, flying near discovered space Nodes allows fast, efficient travel from Mercury to Neptune in one week(-ish), but the stars are just beyond our reach. Lost relics of the ancient Progenitor species hold keys to cosmic mysteries and powers over mind and matter. Our fellow Solarians possess abilities like psychic powers, chromatic color-changing skin, emotion-broadcasting, and survival in the void of space. Humans have found their place as peacekeepers and negotiators, maintaining a tenuous balance to unite all Solarians against Invader threats.

Space station battle

In this setting, strike teams on Earth secure the perimeter of chaotic portals to interstellar worlds to stop alien monster incursions. Misfit bounty hunters veiled in the Asteroid Belt take on questionable courier, manhunt and "acquisition" work for Credits. Veteran soldiers man the front lines against invaders, on jetpacks or in squadrons surfing Saturn's rings. Brave scouts explore the frontiers of deep Node space in search of fortune and glory. Mad scientists search remote moons and lost planetary continents for relics and ancient knowledge to stop the next Invader menace. And sometimes a Spaceport custodian hears a heap of last week's rotten breakfast start singing...

Ship to Outer Planets

Fight unique monsters inspired by great works of sci fi or space shoot-em-ups. Explore alien worlds and immerse yourself in exotic civilizations and cultures. Chart a course, plumb the depths, scavenge cities and make deals with the devils you know (or the ones you don't) in an epic space adventure!

Sub-light Nexusdrive space travel can take you anywhere -

Inner Planets

- from the Sun's corona -

Outer Planets

- to the Kuiper Belt.

Local Aliens (Solarians)

Get to know your neighbors, maybe skip the fluorocarbon cookies.


Stories of fortune, trial and triumph in the perilous Solar System.

What does it mean to be human in a strange neighborhood?

Welcome to the Inner Planets, where unlike the dense Outer moons, every species has just one big homeworld and no extras to spare. The Venusian surface is a raging acid inferno, while its ancient cities float in its safer skies. Humans, as the newest space-farers on the block without the baggage of ancient grievances, established Earth as safe neutral ground for diplomacy between Solarians (while everyone just ignores the Gemini Zones in the room). Outside of the main Martian cities, the rough red sands of Mars harbor brutal nomadic societies of derelicts, bandits and wanderers, and the occasional colossal megaworm. The Martian underground is replete with vertigo-inducing giant caverns and even more crime and villainy than the surface, but at least you're out of the sand.

Venusian Cloud City of Zresthra, Venus

Approaching Sacral District of Kalimnit Nierath, Greater Zresthran Drove.

Pictured: Approaching Sacral District of Kalimnit Nierath, Greater Zresthran Drove. The cloud cities of Venus float high above the hellish surface. Enjoy your stay in a comfortable, Earth-like environment, and while you're at it, go cloud surfing. Just don't make the city angry. Venusians revere their city stewards as keepers of a sacred connection to their home - and paradise can turn hellish real fast.

Martian Subsurface Outpost

Traders Seeking Shelter at Outpost Resmor near Galaxius Mons, Mars

Pictured: Traders Seeking Shelter at Outpost Resmor near Galaxius Mons, Mars. The bustling, cavernous underworlds of Mars and the worm-filled wastelands above connect via these city-station outposts that serve as the few remaining neutral zones of the war-torn planet.

The Outer Planets are swarming with moons. A lot of them. Not ten, not twenty but hundreds of moons (Inner Planet folks especially get this number wrong). We humans thought, like early Martians, that these moons were just big dumb lifeless rocks like most other objects we see near the stars. It turns out many of these big dumb rocks have had Nexusdrive waystations, colonies, and entire terraformed civilizations hidden by ancient (Progenitor?) cloaking tech all along.

The largest moons of the gas giants are the homeworlds for their native Solarians. Nobody lives "on" the gas giants themselves except space miners and maniacs (a Venn diagram that is usually a circle). They extract Cores to fuel technology that uses the fundamental cosmic forces of Gravity (Jupiter), Plasma (Saturn), Quantum (Ur) and Dark Energy (Neptune). Each particular civilization has been harvesting these energies for a while, so expect them to be expert-level with their particular planet's Coretech. Not to say that you can't find good Void Coretech on Venus, but it might work a little differently after being tinkered with by so many mystics.

The Plutonians, as expected, are an odd case. They reside mostly on Pluto and Charon in the Kuiper belt, and keep their source of Void energy Cores a closely-guarded secret. Outsiders have many theories - the top two are that it comes from a Void rift in Charon's shadow, or that there's a "ghost giant" planet looming deep in the Kuiper belt (at least, that's what the folks in the Kuiper station pub will tell you so they can win a bar bet).

Jovian Grav-opolis of Anat, Ganymede

Jovian Gravitāte-Pilseta (Grav Pillar) near Kalnu Sola Waterfront, Ganymede

Pictured: Jovian Gravitāte-Pilseta (Grav Pillar) near Kalnu Sola Waterfront, Ganymede. Anat is a bustling seaside Jovian city with dynamic people, vertigo-inducing gravity architecture and interplanetary art collections. When visiting be prepared for an emotional roller coaster - traditional Kustiva (emotion broadcasting) is core to Anatian culture.

Saturnine Spaceport of Adiri, Titan

Approaching Ion Storm near Ligeia Marie Shoreline, Titan

Pictured: Approaching Ion Storm near Ligeia Marie Shoreline, Titan. Outside of Titan's Plasma-tower bastioned capital cities are lush jungles harboring terrifying leviathans that are some of the largest and fiercest creatures in the Solarian System. In a way, Titan resembles a primordial Earth... just don't make that comparison to the proud locals.

Neptunian Dark Energy Phased Dimension, Triton

Causeway to the Ancient Imperial Capital En-Rul-Jut

Pictured: Causeway to the Ancient Imperial Capital En-Rul-Jut. On Neptune's largest moon, Triton, the Neptunian civilization has mastered Dark Energy manipulation. This Core technology phases the user to adjacent, parallel dimensions that exist in our time but in a different dimension of space. In the shadows they say there's a conspiracy to twist ancient laws around these dimensions and regress the modern capital cities of Triton to past historic ages, where a thin mask of civility once concealed vicious brutality.

If you're going this far out, have a damn good reason.

The major planets are a few among multitudes of lesser known and even uncharted Solarian planetoids and celestial bodies. Such places may be sparsely populated at best and dangerously unknown at worst. The few survivors of doomed remote exploration crews return with reports of strange creatures, unexplained phenomena and seductive alien women (That last group? Space lunatics).

Sun's Shadow, Mercury

Progenitor Relic Excavation Site.

Pictured: Progenitor Relic Excavation Site. Mercury's perilous surface is uninhabited but dotted with monumental ruins. Answers to who and what created them remain a mystery, inspiring intrepid explorer teams to investigate and discover new relics there.

Brutal temperatures and solar winds have kept all but the bravest researchers and explorers at bay from the Sun's messenger. No known Solarian species calls this place their homeworld, but the relics and ruins show signs of an ancient civilization that theorists claim seeded the Solarian system ages ago (The Venusians are certain of it). It would certainly explain the mysterious ancient cloaking technology suspended in a network of tiny celestial objects that travel in a suspiciously tesseract-like formation around the entire Sol system.

Baltic Gemini Zone, Earth

Emerging Gemini Zone Disturbance in the Crimean Peninsula.

Pictured: Emerging Gemini Zone Disturbance in the Crimean Peninsula. Gemini Zones are rife with chaotic dimensional bubbles that overlap two locations in space across unfathomable distances.

No one knows how it happened, but after a Coretech incident went horrifically awry, parts of Earth suddenly got a lot more... interesting. Welcome to the unique and terrifying frontier of the Gemini Zones. Within these restricted zones, dimensional bubbles may spontaneously erupt, sometimes for moments, sometimes indefinitely. Inside of these bubbles, Earth's surface overlaps with the surface of another world - we can only surmise this is some moon or planetoid elsewhere in the galaxy. And sometimes, things emerge...

Smuggling and Piracy in the Asteroid Belt

Multimodal Logistics Headquarters, FULCRUM Federated Corporation, Ceres.

Pictured: Multimodal Logistics Headquarters, FULCRUM Federated Corporation, Ceres. They say you only have two out of three choices when moving your goods across Sol: fast, safe, or cheap. FULCRUM achieves all 3. (They didn't say it had to be legal.)

Near the Inner Planets are rogue comets, asteroids and other transient astral bodies. The Asteroid Belt in particular is unclaimed territory, and deadly competition exists for precious mineral harvesting there. Within the greater Asteroid Belt lurks the dwarf planet Ceres, where you can find the mechanized heart of quasi-legal interplanetary shipping operations. FULCRUM in particular is notorious for this, but plenty of other rogue corps slip away with ill-gotten goods in the shadows of the swarm. Oh and pirates, pirates everywhere.

Interplanetary Node, trans-Neptunian region

Dimensional-Topographic Image of Node A678-Ɣξ.883.

Pictured: Dimensional-Topographic Image of Node A678-Ɣξ.883. Interplanetary Nodes serve as efficient lanes and somewhat-safe harbors for space travelers.

Between the planets, Nodes exist throughout interplanetary space. These Nodes, or localized flux distortion points, allow nearby Nexusdrive space vessels to travel quickly while using minimal fuel. When one leaves the safety radius of known Nodes, they enter the Drift - the void of space where Nexusdrive fuel does little or nothing. Few ever escape the Drift (save for the lucky Outriders who manage to skim its penumbra and discover new Nodes they seek for profit). Don't trust any other ships with a tow cable bigger than you, they just might swing you into it...

Ariel's Amethyst Archipelago, Ur

Geothermal tidal islands near the Finvara region.

Pictured: Geothermal tidal islands near the Finvara region. The Moons of Ur (named the Ur-Planet or Origin Planet by its synthetic Uranian natives) feature some of the most unusual terrain in the Sol System.

The Outer Planets have many larger worlds to explore. Did I mention they have a lot of moons? The largest moons have unique biomes, weather and geology, and most of them have distinctly hazardous terrain, weather, creatures, erratic phenomena influenced by the planet's energy signature, or all of the above.

Vulcan Planum, Charon

Stygian Aurora emergence above Charon's largest plana.

Pictured: Stygian Aurora emergence above Charon's largest plana. Energy signatures from the Outer Planets and Kuiper Belt regions sometimes cause strange local aberrations in the laws of physics. Better hope it's not a micro-magnetar or the like; a magnetic field strong enough to rip a Solarian to pieces would probably ruin your day. In the danger there's unique beauty to find, like the hypnotic and space-warping Stygian Aurora, a result of Void energies disturbing the Charonic exosphere.

The twilight domain of the Plutonians is touched by strange traces of Void energy. Its space has rifts, spatial and dimensional distortions that make travel in the Drift an especially dangerous proposition. This region has a collection of mid-sized objects, dwarf planets and cubewanos, and some of these bodies glow with erratic Void energy distortions on their surfaces.

Players may choose to play one of nine Solarian species with unique traits, abilities and cultures.

Cypher Player Character Types

With the Cypher System, players may choose a custom but simple combo of Descriptor, Type and Focus to make a unique character. Four Types (similar to Classes in other games such as D&D) with examples are provided below. The four character Types are Trooper, Sharp, Syphon, and Vocator.

All Solarians share a common upright symmetrical humanoid body structure, with rare exceptions. However, expect wide variation in body size, shape, and characteristics when encountering the Solarians shown below.

Plantlike Venusian Syphon

Mea-liri, an Adventurous Venusian Syphon who Channels the Sun.

Pictured: Mea-liri, an Adventurous Venusian Syphon who Channels the Sun. Venusian homeworld culture is intimately connected with channeling mental powers, and its spirituality centers around the fabled Progenitors of all Solarians. Their monastic cities float serenely above the absolutely terrifying hellscape of the Venusian surface. No wonder they're so calm.

Tall Venusians are botanical humanoids with forms that can resemble many beings within our plant kingdom. Most frequently they have tough barkskin and possess multiple vocal chambers, and are naturally adept with powers of the mind.

Empathic Human Vocator

Xencara Pollux, an Appealing Human Vocator who Commands Mental Powers.

Pictured: Xencara Pollux, an Appealing Human Vocator who Commands Mental Powers. Humans' shield of interplanetary neutrality can be handy in a pinch, just don't go around kicking down doors in the blackest depths of Ceres thinking you have full diplomatic immunity.

Collaborative Humans easily bond with alien pet companions and have protected outsider status within Sol.

Rugged Red Martian Trooper

Skargoth, a Lucky Red Martian Trooper who Murders.

Pictured: Skargoth, a Lucky Red Martian Trooper who Murders. Expect a meeting with the most placid Olympus Mons Red Martian to involve some property destruction. All in good fun!

Red Martians are predominantly large, intimidating and brutally strong. Many also have a natural proficiency for hunting, whether it be for food, bounties, or market deals.

Cunning Green Martian Sharp

Vondrel 'Squibba', a Learned Green Martian Sharp who Wears Power Armor.

Pictured: Vondrel 'Squibba', a Learned Green Martian Sharp who Wears Power Armor. While the Red Martians' home is the dune-capped overworld, the Green Martians took root in the caverns of the underground.

Generally small, cunning and quick, Green Martians make excellent pilots, with reaction speeds that even surprise Uranians (not that they would ever admit it).

Emotion-Broadcasting Jovian Vocator

Natrok Di Trom, a Charming Jovian Vocator who Commands Mental Powers

Pictured: Natrok Di Trom, a Charming Jovian Vocator who Commands Mental Powers. Jovians out of all Solarians lead the pack in performing arts and entertainment thanks to their unique empathic abilities. Meet a master of their emotion arts and in their presence you'll feel... well, whatever they're feeling, really.

The most distinctive feature of Jovians is the sensory organ on their heads that enables them to broadcast their emotions to others. As masters of Gravity, Jovians are usually comfortable in all unusual gravity situations except low-G and zero-G.

Reptilian Saturnine Syphon

Kle Ro Ta, an Inquisitive Saturnine Syphon who Rides the Lightning.

Pictured: Kle Ro Ta, an Inquisitive Saturnine Syphon who Rides the Lightning. Natives of Titan are the most exhausting of the Saturnine; expect any conversation with a typical Titanian to be long-winded and dramatic. Drop a fork at the dinner table and you may be cursed, challenged to a duel, then deemed unworthy of challenge so they can lament their victory by default.

Saturnine have reptilian physiology, four dexterous arms and an affinity for technology, enough that some claim they invented the Uranians (yes, as in "invented an entire civilization").

Synthetic Uranian Sharp

ILAV-42, a Calm Uranian Sharp who Controls Gravity.

Pictured: ILAV-42, a Calm Uranian Sharp who Controls Gravity. If you nudge a Uranian for their opinion on the "Why Don't You Call the Saturnine Lord of Technology 'Daddy'" question, be prepared for a nuanced, reasonable take on your obvious provocation.

Uranians are synthetic lifeforms imbued with a life-spark of Quantum energy, living in vast machine worlds orbiting their home planet of Ur (Uranus, as we once called it).

Shifting Neptunian Sharp

A-vot ✫, a Sly Neptunian Sharp who Dances With Dark Energy.

Pictured: A-vot ✫, a Sly Neptunian Sharp who Dances With Dark Energy. Neptunian homeworld culture is rife with nuanced protocol and structure, and since they use skin color shifts to communicate context, they have the most difficult of all Solarian languages. Again with the 'dropping a fork' example, if you were to do this at a Neptunian table, you would be asked a question about the weather last twilight that implies you are too much of a slob to get out of bed early. And most of that subtext would take place in colors they had generated on their skin. Easy.

Neptunians are humanoid aliens with smooth, aquatic features and chameleonic color-changing skin that is typically cyan-to-blue while at rest. Their multinucleate physiology enables limited adjustments to their forms, like a mimic octopus.

Space-Adapted Plutonian Trooper

Uquei, a Calculating Plutonian Trooper who Drives Like a Maniac.

Pictured: Uquei, a Calculating Plutonian Trooper who Drives Like a Maniac. Native to the far outer reachers of Pluto and the bodies in the Kuiper Belt, Plutonians have a reputation for being weird that even the Uranians have trouble quantifying. Perhaps it's the isolation, the cold or the vast distances. Either way, when the Abyss gazes back at a Plutonian, it just might flinch.

To Terrans, Plutonian forms resemble the fabled "Grey" alien, with smooth heads and solid dark eyes. Life in the resource-scarce outer edges of the Sol System has led to many adaptations for such a limited environment. Their semi-porous interiors allow them to cycle air rapidly through their bodies, and some have enough collapsible internal structure to compress themselves in tight spaces. They require the least air, food and drink of any Solarian, and can even survive for minutes in the void of space, but their structure can make them deficient in brute strength.


"Great Ungaunt. We have confirmed. Their small claws leave exposed their giant underbellies. A strike will crack their shell where it is thin." - Under One Star

Invaders are the unknown, dangerous and powerful alien lifeforms in our universe that come from beyond our worlds, causing chaos and destruction. Their motivations, strengths and weaknesses may vary, but at least we Solarians have always stopped their invasions.

For now.

Mind-Controlling Primarch

Primarch Sapient Form.

Pictured: Primarch Sapient Form. The outbreak of these creatures nearly destroyed Titan, but they were stopped by a motley group of adventurers and a brave contingent of Vidluminan militia.

A Venusian researcher on the remote island of Vidlumina discovered this rapidly-multiplying Invader Primarch species. It has a lifecycle of growth fueled by the consumption of brainwaves.

For the closure we always wanted but never got.

Read a complete narrative to explore the worlds of Defend the Sun. Each prose short story is a self-contained "sequel" to a real tabletop game session.

Gravity Ghosts - A mob hit gone horribly right, in the dark spaces between. Read story ➝

Themes: Action/Adventure, Buddy Cop, Criminal Underworld
Reading Time: ⧖ ~15 minutes

Time's Amber - Watching time through both the vanishing eye of the storm and the determined eye of a scientist. Read story ➝

Themes: Drama, Apocalyptic Log, Science, Discovery
Reading Time: ⧖ ~15 minutes

Under One Star - Discovering what it takes to unite all fronts, all people, all selves against what we fear most. Read story ➝

Themes: Drama, Space Opera, Action, Romance, Mind, Redemption, Unity
Reading Time: ⧖ ~35 minutes

More to come