Sol

Sol is an almost incomprehensibly huge and inhospitable place. More than a million worlds the size of Terra could fit inside the burning star without filling it up, and its coolest sections are still more than twice the temperature necessary to vaporize steel. Yet despite the harshness of its environs, the sun is still host to organic life. Within its fiery depths, massive dolphin-like fire elementals are spontaneously born, rolling and diving in the seas of flame. Deeper down, where the heat and pressure grow so great that the combustion gases change into plasma, some of this strange energy takes on a life of its own. The resulting plasma oozes are shimmering entities ranging in size from that of terrestrial elephants to blistering mountains, and the mindless giants slither endlessly through the flaming murk.
Environment: Giant ocean of fire and heated gas.
Ecology: Low but thriving.
Natives: Primitive
Notable Locations:The Burning Archipelago, The Silent Sanctum, The Sleeping Sea, Starheart.
Mercury

The rocky world called Mercury is the closest planet to Sol. A relatively tiny world compared to Terra, Mercury is composed primarily of iron and other dense, heavy metals encased in a crust of rock and silicate dust. While splashes of color and weird rock formations are not unknown, most of Mercury's surface is drab desert and sharp-edged hills, all pockmarked and scarred by countless meteorite impacts, some of which created craters with miles-high mountain ranges surrounding their rims. With no atmosphere to speak of—those little bits it attempts to hold on to are regularly blasted away and replenished by the solar wind—the planet has nothing to help it regulate temperature, so conditions can reach 800 degrees Fahrenheit in the full brunt of Sol and drop below –300 degrees in the shadow, resulting in baking badlands matched by large quantities of ice in deep craters and sheltered polar valleys.
Environment: Airless wasteland. Fiery hot days and freezing cold nights.
Ecology: None natural, Machines in Decline
Natives: Highly Advanced Robotech
Notable Locations: The Automatrix, Cities of the First Ones, Epoch (Capital City), The Fields of Judgment, Horsethroat (Human Colony), The Ice Wells, The Midnight Trenches, Sea of Glass, Sun Basin.
Venus

The world of Venus is the complete opposite of Mercury. Where Mercury is rocky and bare, Venus is humid and humming with life, its thick blanket of atmosphere trapping the sun’s energy and making the surface a lush, steamy paradise. Jungles abound here, full of great broadleafed trees that sometimes stretch several hundred feet into the air, with branches large enough to support a house, or else cluster in masses so thick that the sun can barely penetrate to the floor of strange and primeval swamps, where gnarled mangrovelike roots form whorls and hollows housing all manner of creatures. Oceans of colored mist and gas vie with more conventional seas to provide habitats for innumerable species, from cannibalistic selkies and schools of semi-intelligent fish to the elephantine isopods that trundle across the sea bottom, the cracks in their glowing armor providing safe havens for delicate seahorselike symbiotes. Given the sheer amount and variety of life on Castrovel, it’s small wonder that legends of “the Green Star” often associate the world with lust and fertility.
Environment: Planetwide Jungle
Ecology: Thriving
Natives: Low Tech
Notable Locations: The Colonies (Human), El (Human Capital), Lashunta City-States, Ocean of Mists, Qabarat (Capital City).
Terra

Terra is the third planet from Sol, and the largest of the Solar System's terrestrial planets. Astronomical literature from other worlds often references it as “the Cage,” presumably alluding to the world’s status as the prison of some dormant Cosmic Entity. Terra itself needs no overview, it being an exact replica of our planet.
Environment: Varied
Ecology: Thriving
Natives: Highly Advanced "Retro" Tech
Notable Locations: The Ten Metropoli, Skydock, City of the Faceless, The Moonscar.
Mars

For millennia, the people of Terra have looked to the world of Mars as a harbinger of war, seeing in the Red Star’s bloody hue a martial blessing and portent of coming battles. Yet few have ever realized how close their stories come to the truth. Mars is a harsh world. With only a thin layer of breathable atmosphere to support life and keep the planet insulated, it is mostly cold desert, the planet’s red color stemming from the vast plains of iron-rich sand and stone that cover much of its surface. Once, in its geological youth, Mars played host to great seas rich with life and nutrients, yet these have long since evaporated, run deep underground, or condensed into the thick ice caps at either pole. In their wake, they left only dusty mountains and dead sea-bottoms, with strange plateaus and weirdly organic rock formations rising from the drifting sands. In places, the sides of knife-edged canyons reveal layers of sediment containing the strange skeletons of colossal creatures from a lost era, their bones crafted into ornaments and weapons by savage desert tribes who still tell stories of a time when the land was rife with seas and monsters, racial memories of an epoch before the planet’s slow decline.
Environment: Desert Tundra
Ecology: In Decline
Natives: High Tech (in decline though)
Notable Locations: Arl (Capital City), The Hall of Reason, The Hivemarket, Ka "Pillar of the Sky", Maro (Human Colony), The Winderlands.
Juno

Juno, also known as “the Line,” draws its title from the fact that it is tidally locked, with the same hemisphere always facing the sun. With one side of the planet baking in the constant light and radiation, and the other losing its heat to the darkness of space, the thin atmosphere of Juno is unable to fully distribute the energy, resulting in one side that’s blistering hot and another that’s freezing cold. Only along the terminator line, the narrow band where day meets night, are temperatures favorable to conventional animal life, and it is here that Juno’s civilization has flourished, encircling the planet in a bustle of activity. Steamy jungles and tiny tropical seas populate the sunward side of the band, filled with cold-blooded reptilian creatures that bask in the eternal afternoon sun, while farms and fields occupy the majority of the sunset, and warm-blooded predators stalk the twilight of the opposite side, becoming steadily more alien as they pass beyond humanoid-held lands and into the true black of Darkside.
Environment: Sun Side: Burning Desert, Dark Side: Ice Fields, Terminator Line: Tropical Paradise.
Ecology: Thriving (Terminator Line)
Natives: Steampunk
Notable Locations: Fastness of the Ordered Mind, Kashak (Friendly Capital City), Outlaw Kingdoms, Qidel, Sun Farms.
The Diaspora

Unlike an asteroid belt formed normally during a solar system’s birth, the Diaspora still holds many traces of its violent birth. While most of the asteroids and dwarf planets contained within its shifting mass are nondescript, lopsided rocks of stone, metal, and ice, some still bear identifiable traces of the civilizations that were destroyed in their formation. Individual asteroids might contain a few chiseled words or chunks of a ruined city block, while whole fields of crumbled buildings and other artifacts might spin together in a mass, mysteriously spared by the cataclysm that ripped the worlds apart. Perhaps the most amazing thing about the Diaspora, however, is the fact that it remains inhabited.
Environment: Normal Asteroid: Airless Wasteland, Sarcesian Creche Worlds: Terraformed Forests and Plains.
Ecology: Thriving (Creche Worlds)
Natives: Highly Advanced Magitech
Notable Locations: The Creche Worlds, House of the Void, Nisis (Capital Creche World), The River Between, The Vacant Halls (Former Capital), The Wailing Stone.
Pluto

The calamity that destroyed Pluto is a mystery. Some theorize that the Plutonians themselves were responsible for the destruction of both their world and the Diaspora, seeing the Sister World as rival to their own self-important majesty. According to the residents of the Diaspora, the destruction of their ancestral homes was caused by an enormous interplanetary weapon crafted by the Plutoians, an engine of annihilation so powerful that the mere backlash from its successful firing set the atmosphere of Pluto aflame, burning off the life-sustaining gases in a worldwide firestorm. Cities burned and blackened, and seas boiled and condensed into sludge. Most residents of Pluto were killed instantly in the cataclysm. For the few thousand who survived in self-contained environments and secure bunkers, it was the beginning of a new era.
Environment: Radioactive Wasteland
Ecology: Stagnant
Natives: Highly Advanced Cyberpunk Tech
Notable Locations: Church of Silence, Facinora Basin, Halls of the Living, Remembrance Rock, The Sentinel (Capital City), The Thousand Moons.
Saturn

Past the Diaspora, the familiar rocky worlds of the system’s interior give way to a new type of planet, the two titanic gas giants who trade a firm surface of rock and metal for thick expanses of gas vast enough for all the other planets to disappear into without a trace. So large are these goliaths that some of the many moons held fast by the giants’ massive gravitational pulls are nearly the size of planets themselves. Saturn is the closer of the two, with the major differences between it and its larger counterpart, Jupiter, being its peach-colored complexion, its smaller number of significant moons, and its bright rings of dust, which are so massive as to be visible from Terra through a basic telescope. In addition to the rings and their myriad shepherd moons—some no larger than a house—the planet also has several populated moons.
Environment: Planet: Gas Giant, Moons: Varied
Ecology: Varied
Natives: Low Tech-High Tech
Notable Locations: Titan (Most Populated Moon), Rhea (Isolationist moon), Mimas (Human Colony Moon), Tethys (Hive Moon), Dione (Poisonous Moon).
Jupiter

Jupiter is far and away the largest planet in the solar system. Huge and swirling, with blue and purple clouds, it hangs in space surrounded by the dozens of moons that make up its “children.” A gas giant, it has no true ground, only countless miles of drifting atmosphere and gas seas that gradually condense as one falls lower into their swirling torrents. Yet despite this lack of terra firma, Jupiter is inhabited by some of the most distinctive and widely varying beings in the solar system.
Environment: Planet: Gas Giant, Moons: Varied
Ecology: Varied
Natives: Planet: High Tech, Moons: Low Tech
Notable Locations: Eye of the Ancients (Super Storm on Planet), Io (Crystal Moon), Neptune (Water Moon), Europa (Forest Moon), Ganymede (Irradiated Moon), Callisto (Volcanic Moon).
Minerva

The rocky planetoid known as Minerva is tiny compared to the other worlds of the solar system, and immediately establishes itself as an anomaly by orbiting Sol at an angle far out of the ecliptic, almost perpendicular to Terra's own path. Both of these suggest that the planet is in fact a captured object, something formed elsewhere which drifted through the system and was drawn in by Sol's gravitational well. What keeps the world from being written off as simply another captive asteroid is not Minerva size, but its mystery.
Environment: Outer Shell: Barren Wasteland, Inner Halls: Techno-Organic Star Ship.
Ecology: Stagnant
Natives: Highly Advanced
Notable Locations: Chamber of Life, Empty Halls, Grandfather Stone, Sleepers Below, Worldheart.
Ceres

Ceres is an enigma, a dark mystery to even the greatest of planetary scholars. Unreachable by all but the most advanced starships, Ceres is the only world in the system not connected to any others by the interplanetary portal network, thus adding to its sinister legend. Some say that it is a world of monsters, or the home of an ancient god just now waking from a million years of dark slumber. Historical writings seem to link it to the spaces between the stars known as the Dark Tapestry, or the mysterious and terrifying being called the Dominion of the Black. Perhaps Ceres does not even exist entirely in this dimension, and acts as a link between this universe and others. Whatever the truth, for thousands of years the planet has unnerved astronomers who, peering at it through their telescopes all report very different descriptions, from a terrestrial world with atmosphere to a ringed gas giant to a dark and lifeless rock—even when observing it through the same shared telescope.
Environment: Unknown
Ecology: Unknown
Natives: Unknown
Notable Locations: Black Citadel, The Gravid Mound, The Loving Place
Levels of Technology
Low Tech: Below Modern Real World
High Tech: World of Tomorrow Level
Highly Advanced: Incredible Level