I ran a couple of forum searches and gleaned there is no central repository of planets or special locations for RT GMs.

Everyone probably has at least a couple of good ideas, right? I'm currently working on Death World Fortuna: a mix of Gold Rush California (culturally) and Louisiana (geographically). I will post it here when completed, but I am getting the ball rolling now.

I envision this topic as a quick reference for backdrops for encounters or even locations for minor endeavors. It should also be a way to leave the players with a sense that the galaxy is a much larger place than any one GM may create; over 200 billion stars in the galaxy! In order for characters to access these locations as backgrounds, as well, I suggest utilizing the 40k planetary classification system as outlined in RT Core Rules and Into the Storm, to wit:

• Agri World
• Cardinal World*
• Cemetery World
• Civilized World
• Crone World*
• Daemon World*
• Dead World
• Death World
• Feral World
• Feudal World
• Forbidden World
• Forge World
• Fortress World
• Frontier World
• Imperial World*
• Knight World*
• Maiden World*
• Mining World
• Penal World
• Pleasure World
• Research Station
• Shrine World*
• Special
• Tomb World*
• War World

*These aren't official planetary classifications, in RT, according to my research, or in some cases the rules considered them a sub-set of the designate of "Civilized World". Yet, they are found in abundance in other Warhammer 40k materials, and it would be handy to use them for quick reference.

In other words, a GM could come to the forums type "Gazetteer Depositorium" and / or "Forge World" into the site search engine and then may immediately reference this topic thread. So, when I have completed my planet, I will reply in this topic with "Death World - Fortuna" in the post's title.
 

Fuedal World - Cathaarian

The Borslov system, colonized by the Cathaar (wolf / dog humanoids).

A Feudal society that resides on an Agri world, controlled by a large wolf humanoid calling himself “Erof Huf,” meaning ‘The Baron’ in High Gothic. He rules the whole world, and hates all other religions with a passion. He believes in many gods, like the Greeks did. There is also a small tyranid infestation on the planet. Most of these are gaunts, but maybe a gene-stealer might spring up and cause discord once the players leave, if not rooted out upon initial investigations/rumors. The wolf / fox humanoids are the Nobles/Leaders with a few rare exceptions, while all the dog or mutt looking humanoids are the labor, slaves, or muscle. Their are obvious signs in hidden underground cave cities / bunkers that a tall lank white skinned humanoid race once lived on their planet. Might even be hidden evidence that they created the race than now reside on the planet.

Contains 5 planets.
1st Cracked raven planet, empty. No moon.
2nd Feudal planet controlled by “Erof Huf.” 1 moon that's empty.
3rd Jungle death world, infested by rogue Tyranids, w/ abandoned human cities. 4 empty moons.
4th Gas giant w/ dead void whale orbiting it. 42 empty moons.
5th Ice covered heavy metal world, with deep xeno ruins. No moons.
3 comets.

Void whales way out in the outer system. They are as big as a raider, pack leaders big as a lightcruiser. Farming then nets exotic meat, oils, and skin that can be used to create void suits.

War World - Gorg

The Gorganian system, colonized by humans and slaugth.

An Industrialist steam engine society, ruled by the slaugth that keep themselves hidden. Only about 1000 slaugth live on the main planet with over 9 billion humans that are in a constant state of war that the slaugth orchestrated. About 4 continents with 5 different factions. Another 10,000 slaugth with 100,000 slaves live on the moon, with underground caverns and labs where they engineer their “constructs” and test them against humans in maze like tunnels. The moon has a hanger base (Str 4), 3 x macrobatteries and 3 x lance batteries, with a +25 detection, hull 120, and armour 24, crew and morale of 140.

System contains 4 planets.
1st Cracked volcano geyser planet. No moons.
2nd Large Earthlike planet colonized by humans controlled by slaugth. 3 moons, 1 with hidden slaugth base.
3rd Gas giant, 1 xeno destroyed space station, 27 moons.
4th Dust stormed planet. 31 moons. All empty.
5 large comets.  1 made out of very rare metals.

Death World / Frontier World - Fortuna

Fortuna Gazetteer

Fortuna orbits a binary star system composed of Zalmoxis Alpha and Beta, which are red and orange mid-sized stars respectively. Fortuna is the fifth planet in a star system of 6. The others are simply named Zalmoxis Prime, Secundus, Tertius etc. Fortuna has no natural satellites, but none would be visible anyway.

Fortuna is surrounded by a thick atmosphere shielding the planet from abundant solar radiation, but also much light. It is locked in a perpetual twilight, never knowing either full night or day. The air is choking with humidity, impenetrable clouds and almost constant rain, which runs from misty drizzles to calamitous downpours. Fortuna is home to millions of ponds, lakes and but a single marine ocean that covers the southern hemisphere. Due to the volcanism spurred by the two stars, there are also many hot springs and geysers. The planet teems with life, most of which is amphibious and carnivorous.

There is a single human colony of a few thousand Imperial citizens.

Thanks to the unstable ground, constant mires and mudslides the colony rises 100m off the ground; built upon enormous ceramite pylons sunk into  bedrock. The settlement is in close proximity to one of the few low-mountain chains, weathered by constant precipitation. These worn rock faces bestow colonists with rich lodes of precious metals and minerals unearthed by steady downpours. Eagerness for these pickings leads to a constant influx of naive Imperial citizens who seek their fortunes in this deadly place. Many who come are killed. Some die asphyxiated in mudslides, scalded to death by geysers, falling from slippery places or eaten by the local fauna. Yet there is never a shortage colonists and this colony has been in operation for over 2000 years. Toxins and drugs which are extracted or rendered from the numerous planetary fauna is a growing industry.

The colony is named Petrus Point after Petrus Kervielus the rogue trader who founded it. (Fortuna is itself named after the trader’s eldest daughter.) Originally Petrus Point was built as a penal colony, but geological surveys quickly proved that Kervielus built a jail on top of a big fat gold mine. Convicts were transferred to other Prison Worlds, in the Expanse, or conscripted as miners. Numerous escapes and thefts lead to the eventual phasing-out of this slave labor practice. Many fugitives survived, however, to live as tribal “mudmen” in the brutal wilds of Fortuna.

Petrus Point

Petrus Point is a boomtown; a place where a few fortunes were made but even more lost. Thousands of thrones in precious metals or gems hinge upon persistence or lucky breaks in the in the bayous and hills of Fortuna. There are those who have struck it rich, but the local economy suffers from heavy inflation due to a lack of goods and services and the general remoteness of the place. Hence, amenities that may cost a few thrones on most Imperial worlds, are far more expensive here. There is very little law save for what the small Adeptus Arbites presence provides. They fight a losing battle; everyone has a price on Fortuna. Theft and other worse crimes are rampant despite harsh, inconsistent justice. Many colonists hire their own bodyguards for protection; as foul play and sabotage seem very common.

Petrus point was originally built as a prison, so space is cramped, often locked and with few exits or entrances. The colonial facility is quite sturdy, however and protect its inhabitants well; keeping dangerous people and creatures at bay. However, the grounds are quite leaky being so ancient, and everyone is too busy doing other things to bother with infrastructural maintenance. Yet exterior doors, windows and gates remain quite strong in spite of this. Hundreds of (former) cells serve as living quarters for colonists. The large open areas, formerly the cafeteria and infirmary, were converted to markets wherein colonists may trade their precious stones or ingots for overpriced amasec, prostitutes or even to be lost in games of chance. Gambling, and cheating at gambling, is all too common in Petrus Point.

Colonists typically labor in 12 hour shifts, either panning for metals in the run-off of the swampy lowlands or by plying one of the many mines that network the weathered mountains. Bands of prospectors are typically accompanied by heavily-armed guards as natural mishap, creature attacks and criminality is a near constant. A single, harried squad of Adeptus Arbites arbitrators utilize the former prison guards’ and warden’s quarters, along with the antique security system, in oversight and to keep things civilized in Petrus Point. However, rumors of their corruption abound amongst locals.

Planetary Defense Forces are composed of several surprisingly well-equipped, dependably-crewed and capable system ships used to ward off pirates, or even especially avaricious Rogue Traders.

Beyond The Pale

Hungry carnivores stalk the wilds and attack lone human targets eagerly. Groups fare much better, but a lack of trust amongst colonists keeps these numbers low. Amongst the growing concerns are bands of "mudmen"; the tribal decendents of escaped convicts and fugitive criminals. Mudmen wear the skins and bones of amphibious creatures and brandish poison-tipped spears and war clubs fashioned from the jaw bones of megamanders. As ornamentation mudmen also decorate their bodies and faces by smearing them with colored mud. Mudmen attacks on miners and prospectors are lately on the rise and may soon result in open assault on Petrus Point; if things do not change.

Over the centuries, several industrial concerns have attempted to construct temporary mining facilities away from Petrus Point, which have all ended in disaster. Their efforts were rewarded by having workers killed often in large numbers or expensive equipment claimed by the muck. Mudmen hate and fear these abandoned facilities and typically avoid them as "cursed". There is still much salvageable equipment even if large-scale mining is impossible.

The Fortuna System

The Binary solar system of Zalmoxis A and B keeps the locals quite warm. All planets have considerable geologic activity and are subject to formidable tidal forces. For example, the lone ocean of Fortuna experiences differences in seal level of dozens of meters every 28 hours. The remainder of the system is thus:

• Zalmoxis I: A small, almost red-hot, planetoid swimming in a sparse and inaccessible asteroid belt.
• Zalmoxis II: A hot ball of rock without atmosphere or satellites or mineral value.
• Zalmoxis III: Another hot rock, as with Secundus. Tertius has a small moonlet, which may be a captured asteroid and one that also appears too round to be natural.
• Zalmoxis IV: Gas Giant with abundant hydrogen, vaporized promethium and other hydrocarbons. Quartus has 7 moons, which remain largely unsurveyed because of the abundant wealth available on elsewhere in the system. It bulges visibly at the equator due to tidal forces.
• Zalmoxis VI: A world of ice and frozen gases with a single small moon. Little to no exploration has ever taken place.

Fortuna Bestiary (of Note):

1. Pink Peril -These are crow-sized frog-like beasts notable for their very bright pink coloration and mouths filled with razor-sharp teeth. These creatures are excellent climbers and are also pack hunters; a dozen or so can easily overwhelm a human. Once a generation they over-breed and are driven into a frenzied plague that blankets the fens and lakes in brightly-hued, noisome death, devouring everything in its path until finally turning on itself. Packs on the hunt use an frightening, persistent and unmistakable call used to herd prey.
2. Megamanders - Large carnivores about the size of a hippopotamus. Megamanders are attracted to moving targets and will try to eat anything that fits in their huge toothless mouths. Excellent camouflage and patience allows them to lurk for hours in ponds awaiting a passing victim. A megamander will leap from cover and attempt to catch prey with its long, sticky tongue. They are deceptively clumsy-looking, but pounce and snare with lightning speed. Hunters prize long megamander tongues, which are made of sweet, delicious and tender meet.
3. Bufola -Enormous toadish animals larger than elephants, and about twice the mass. Bufola are herbivorous but also extremely territorial and aggressive. Males, in protecting their harems, charge deemed threats, which is almost anything due to poor eyesight. Females are relatively docile, but when threatened glands behind their eyes can squirt concentrated poison. Bufola are hunted for their abundant meat and tough, but easily-worked hides. Mudmen tip their spears with Bufola cow poison, which is a powerful paralytic that also causes excruciating muscle cramps.

Endeavor Ideas:

Colonists are tire of constant crime. The ever-inflating cost of guarding has lead to the formation of a governing council. Its first official act is to petition the Administratum for re-assessment, which would result in better security but also a steep increase in tithing. An assessor and army of bureaucrats seek transport to Fortuna and further protection as they perform their unpopular (with many still) duties.

The mudmen are revolting! A mudman leader has broken with his culture, braved an abandoned mining facility and armed his tribe with industrial equipment and Imperial weapons tech. They seek to vanquish the “ rain and thunder guardians” and ascend to their rightful place in the paradise of the “glowing sky palace” that is Petrus Point.

A band of big game hunters invite the explorers to stalk megamanders. Is this party legitimate or do they simply wish to kill wealthy prospectors and steal their booty? Or both?

The only shrine to the God Emperor at Petrus Point is a small, neglected chapel. An enterprising missionary might bring religion (and law and order) to the lawless.

Maiden World - Illiad

The Illiad system, colonized by humans.

An Industrial Imperial planet that has various religions. Could be swayed, other than a small sect not wanting Imperial control that could cause a problem later if not rooted out before leaving Preachers their. Not capable of space travel. First two planet ecosystems seem to be perfectly perfect for human colonization, with no predators or dangerous fuana to speak of.

Contains 5 planets.
1st 9/10 Waterworld colonized by humans with fishing fleets and huge cities floating on the water. Has a couple of huge floating battleship/cities that are rebels. All life on the planet is edible and not dangerous to humans. 1 empty moon.
2nd Forest planet, a paradise for colonization. Has 5 huge archaeotech human cities that are empty. 2 moons that are empty.
3rd Gas giant with 3 derelict space stations. Very decayed and damaged. 44 moons, all empty.
4th Gas giant, with a damaged Yu'vath battleship hidden in the depths of it. Orbiting around the planet are debris from 5 destroyed human ships and 2 eldar ships. Maybe with some components still able to be salvaged and/or archaeotech. 23 moons all empty.
5th Almost an all rocky planet with human mining colonies long abandoned, deep ravens and caverns on the planet. Also has a crashed battlecruiser on the planet hidden in a deep raven covered by dust and rocks. 5 moons, all empty.

P.S.  Ohhhh…. A weee bit more indepth than what I was thinking. ;) 

Feral World - Dolorium*

I am unable to find any write-ups regarding this planet in any canon material (that I own or is available online). If such arises, or if you have other plans for Dolorium, substitute "Sevel" and "Sevelans" for the planet's name and the name of its people.

Dolorium is in orbit around a yellow medium-sized star, known as Nityanda, in a system of 7 planets and a sizeable asteroid belt. It is a Feral World, but was originally a human colony dating from the Dark Age of Technology. It was destroyed in a series of unfortunate events that, nonetheless, typified the  arrogance of that age. The Nityanda System may be found in the sub-sector Cinerus Maleficum.

The planet features 3 large continental landmasses and the remains of a fourth, which was obliterated in an asteroid strikes that destroyed the colony’s population center. It has a variety of biomes; hot at the equators and cold, frigid with ice caps at the poles.

Dolorium Gazetteer

Dolorium is a terrestrial planet larger than Holy Terra but with less mass; yet still having approximately the same gravity. It has no satellites but has a belt of thick, impressive rings, which are the remainder of its only moon. Dolorium provides plenty of fresh water and edible plants and animals. Many minerals and metals (common throughout the galaxy) are rare enough locally that they will never be extractable for large-scale industrial purposes unless imported. Thus metals are coveted by natives and used for only the most important and personal uses.

The remainder of the solar system is thus:

Nityanda I: Inhospitable ball of rock with 2 moons.
Nityanda II: Small terrestrial planet with no atmosphere and extremely cold, but with ice below its crust.
Nityanda III: Small Gas giant with a mostly hydrogen and helium atmosphere. No moons but  dozens of moonlets and asteroids in orbit.
Asteroid Belt: Full of thousands of planetoids. Extensive exploration revealed hundreds of ancient, but salvageable tomb ships, filled with the remains of those trapped in space in the comet strike. If the terra-forming engines were not destroyed along with this planet they might be found here.
Nityanda V: Gas giant, very similar to Nityanda III, but much larger with 9 moons.
Nityanda VI: Inhospitable Ice World; no atmosphere all frozen gas. One moon.
Nityanda VII: Tiny terrestrial planet, perhaps VI’s moon knocked from orbit. This planet was submerged in a warp storm, which otherwise only surrounded the system, and may hold terrible secrets.

History of Heretics

During the DAoT Dolorium was a bustling, functioning colony, well on its way to becoming an established planet. Colonists dwelled in ergonomic subterranean dwellings or in one of the two major population centers; a giant factory complex facility or the planet’s only city. Although the planet was mineral-poor, it has fine soils that supported much agriculture and the colonists were able to import needed materials. Much of the colony’s employment was rendered off-world, with the majority planetside labor tended by a sizeable population men of iron.

The colony boasted a population of almost 500 million. Many were employed in a factory complex which was concerned with constructing materials for the terra-forming experiment taking place elsewhere in the system. Metals and mineral needs were supplemented by claiming an small(er) asteroid belt. Inside the 3rd orbit.

The experiment involved the conversion of the 5th planet, a frozen ball of ice, into a world with a controlled green-house effect rendering its surface with habitable, if not comfortable, temperatures. This planet was a cold, but terrestrial world having a thick crust of ice, containing a high degree of dissolved carbon dioxide, covering its surface. This experiment involved melting the ice and releasing large amounts of sequestered CO2 into the atmosphere.

As the project neared completion disaster struck the colony. During a very critical phase a large, rogue comet struck and obliterated Dolorium’s only moon. The resulting debris rained down upon the planet and largely destroyed the most populous continent, containing most of its citizens and industrial capacity, rendering it into a chain of large islands. Colonists trapped in the void at the time of the disaster were unable to return. They  landed on the 5th planet, slowly dying as meager supplied dwindled.

Of the thousands of colonists trapped in space, unable to return to the colony which lay now largely in ruin, very few were knowledgeable of the terra-forming engines. The experiment, being largely automated, was quickly abandoned and left to its own devices. Dolorium's atmosphere was blanketed in dust, smoke and debris which blotted out the sun. Crops failed and mass extinctions followed. Millions died. As power supplies were depleted, men of iron (utilized as a heavy labor workforce) turned on their masters. As if their luck was not miserable enough, a warp storm enveloped the system, sealing-off Dolorium from outside aid. The terra-forming had been already forgotten for a few generations, by this time.

The experiment continued melting the ice and releasing CO2 into the air of Dolorium's sister world. The planet became a hot house as planned, but the terra-forming continued unabated. A catastrophic geological cascade eventually occurred in the process that destroyed the planet; rendering it into an asteroid belt of slag and melt.

Eventually, the warp storm abated, but Dolorium, alone for centuries without contact, had regressed to pre-bronze era technology. The men of iron had been overthrown, the colony destroyed and the descendents of the colonists reclaimed their mineral poor, but once again life-rich planet. This narrative was pieced together from evidence and what records found in the destroyed continent.

Five Hundred years ago Dolrium was rediscovered as once a human colony. The broken continent (safely isolated from the Doloriumites) was claimed and an Imperial outpost established in the ruins of the remaining city. A generation ago, brave Doloriumites sailed in rafts and canoes to this city following the dictates of a religious prophet. The Imperium then decided that the planet would be slowly returned to the flock.

Present Day

The Dolorium of today is a different planet. Its population reduced to a few million, utilizing Stone Age technology and worshipping the planetary governor as the Herald of the Sky God living in the Forbidden City. An especially egregious governor accepted this role and openly welcomed worship. Once removed from his office, the Inquisition decided to interject missionaries into the population, but continued to allow the governor to be treated as the Star God’s earthly avatar: not worshipped but unequivocally followed.

Dolorium, still able to support much life might one day converted to an Imperial Agri World. In the meantime, there are no overt attempts to completely civilize the population. Missionaries perform this necessary work. Occasional feral ork hordes arise (perhaps from spores were sewn by the comet), but the hardy warrior culture keeps them largely in check. Dolorium provides the Empire of Mankind with large herds of semi-wild grox (sometimes numbering in the millions) and occasional psykers for the black ships as its tithe. There are still ruins to be found throughout the island chains and many original colonists subterranean homes remain buried and undiscovered.

The Worship of the Doloriumites

Their religion teaches them that they once lived in cities amongst the stars; that metals were so plentiful on Dolorium that the Star God decreed that some men be made of it. The Star God further promised that a frozen paradise would soon be thawed and that he would rapture believers to this wonderful place. However, their ancestors grew arrogant and refused their god’s ways. As punishment, he destroyed their great city (raining ice and fire from the sky), in cursing turned some men to witches, plunged the world to darkness and suffered the men of metal to enslave them. He also cursed their world, transforming it into a frigid mockery of the heaven he once promised.

In atonement, the people came back to their god, gained strength from righteousness and banished the men of metal forever. However, it was too late. The warm paradise was gone. Delighted with his work, the Star God promised that if they followed his earthly avatar, he would one day reward them on this earth rather than elsewhere. This covenant was sewn by returning the beasts to the world and fruit and grain that they may all be nourished. The proof of this promise are the shining sky bands, always visible during the day, but gone in the night as a constant reminder to be faithful. Another important aspect of their faith is the appearance of a great comet in the sky, which prophesies great misfortune. This comet returns every 530 (or so) years, but is visible for only 13 hours in an unmistakable display. It is said this is an omen of great misfortune, which is determined by the comet’s visibility. Finally the Sky God sends green minions of evil to keep believers from becoming soft and facile like their sinful ancestors.

Notable Bestiary:

1. Feral Orks – Occasionally isolated spores hatch on the populous continent. Pious Doloriumites form eligious crusades, sometimes lasting years, to eventually vanquish the green skins. One of the 3 remaining continents is completely befouled by the orkish ecosystem. Its isolation prevents any eradication, but also spreading. The Imperium is unconcerned and makes no steps to interfere. Although the continent must one day be sterilized if Doloriums is fit to be an Agri World.
2. Direhawk- This is a very large bird of prey with 10m wing span. This beast large and aggressive enough attack and eat grox, which they do only rarely. Direhawks are also known to attack human-sized prey. The bird kills and consumes food on-site rather than carrying it away to its nest. As supreme a right of passage, Doloriumites will stalk and kill these dining malhawks. Typically this is accomplished by a small group, but especially adept hunters and warriors may kill one by themselves. Feathers are long, sturdy and quite beautiful; a deep, rich brown shot through with iridescent streaks of purple and blue.

Endeavor Ideas:

Down on the Farm: The explorers must vanquish the ork incursion on the soiled continent, in order to prepare the planet for conversion to an Agri World. Natives are eager to a crusades but lack the skill to sail to the land of the Orks. Do the explorers risk the wrath of the Inquisition or Ministorum? Or do they tend to the issue themselves?

Golems Arise: Rarely, men of iron are discovered corroding away in undiscovered pockets. Most are too far gone to be anything but heaps of rust and corrosion. However, some natives have discovered several that are fully functional. If left unchecked, they may again rebel and quickly overthrow their former masters. This technology, although quite heretical, could be come one of the most powerful finds in the Expanse and a boon to more unscrupulous rogue traders.

Apocalypse Now: The current planetary governor has let the Doloriumites primitive devotion go to her head. The explorers are sent to ascertain the depth of her heresy as well as the extent to which she has led the natives astray. Once thie situation is fully ascertained, she must be retrieved for the Inquisition and delivered (alive) for judgement and death. The party must also do something about appointing an interim governor until the Administratum may find a permanent replacement.