Convergence

Orbiting it's Host Star at an average 40AU, the Violet Gas Giant Szanaru travels at a highly elliptical orbit, closing in to the sun as near as 1 AU and being catapulted to an apoapsis of almost 60AU, taking 500 years for a full rotation. Also, due to an overabundance of heavy metals and gases, Szanarus mass is almost 4 times that of a comparable Gas Giant (Jupiter), emiting large amounts of thermal and electromagnetic radiation.
Mindosza itself orbits Szanaru. As Szanaru functions as a fracturing mirror, it keeps Temperatures on Mindosza mild. The thermal heat from Szanaru heats Mindoszas metal core countering the large distance - at times - from the sun. This creates a magnetic field and protecting it from space debris and most radiation and creating a habitable zone for mindosza, despite great variance in distance from the lifegiving sun.
Completing one revolution around Szanaru every 3 months, Mindoszas Mass and distance from Szanaru keeps it from being tidally locked, therefore retaining its spin and a 30 hour day cycle.
However Szanarus close proximity and constant EM Radiation leaves Mindoszas charged with enough electromagnetic energy, to fry most circuits we'd have on earth. Therefore, while clockwork and steam technology has been worked on, further technology may forever be dependant on magical means.
However, while Mindosza is the only known/observable planetoid, Szanaru is only one of seven Gas Giants, called Titans, orbiting the sun. Each of the Titans being large and bright enough in the night's sky to be seen with the naked eye on most nights. Each of the Titans is marked by its distinctive color, attributing them to the 6 elements: red (fire), blue (water), anthracite (metal), white (air), green (wood) and brown (earth).
In the years before the convergence, ancient astronomers noticed the path of these Titans came ever closer to their own. What they did not understand in full, was that all planets share an orbital path at their periapsis. As their respective apoapsis differ wildly from one to another, some orbiting the sun in a few years, others in hundreds of years, the Titans only merge paths once every 2000 years, so knowledge of this phenomenon had never before been recorded.
However, instead of crashing into each other, the seven Titans (incl. Szanaru) merged together and thus the convergence happened. Little is known as to why this happens, but the outcome has been devastating. As the Titans aligned across the mindoszan sky, the elemental powers on mindosza were unleashed. Before that, in the Years and months before the convergence, the increased proximity of the Titans led to increased arcane potential. Magic practitioners noticed this increase, as small spells would create grand outcomes. As they harvested this energy, they relied more and more on magic to solve their everyday problems. When the Titans finally merged across the sky, elemental creatures entered the material plane and laid waste to it. With this apocalypse came the Horrors and other aberrations from the astral plane, that fed upon the unprepared people.
The Denizens of Mindosza had to act quickly and took to the Haven cities, which were build into the mountains or other hard to reach places and managed to withhold the assault. The convergence lasted for about two hundred years, until the first haven cities were brave enough to open their gates and step out once more.
Having had Magic and Technology take care of their everyday needs in the past, Mindoszan denizens lost their connection to the Old Gods, especially while hidden away in the havens. As they were no longer able to gaze to the stars, they failed to look upon their gods as well. However, as their reliance and knowledge of technology and arcane arts was taken from them, some people (re-)discovered that their prayers were sometimes answered and that there were powers in the divine to be found. Thus, the New Gods were born.
With the end of the convergence, most knowledge and technology of the past has been lost to the ages. Some of it might be out there in Ruins and Dungeons to be rediscovered. However, in this new, second age the long forgotten Power of the gods seems to reemerge and grow depending on their following. Some Deitys of the past were forgotten, and others emerged, stronger than ever.
With the effects of the convergence still everywhere around us, every venture into the unknown comes with many dangers, but the promise of treasure and knowledge draws out more and more, young and old to find their furtune.