Malacus system
Malacus system consits of 4 major planets and their moons. It was originally colonized during the dark age of technology. Firs colonists arriwed to Malacus primus and made it their home. The details of this era are skcetchy at best but what has been pieced together by the historians seems to point that the original colonists terraformed several planets and moons in the system. After terraforming a large war broke out that killed most of the inhabitants of the system an the survivors descented to a primitive barbarism.

This was the status of the system when Imperial expeditionary fleet found the system in 480.M38 and categorized it as a feudal world. The Imperial governol, Gaius Malacus wanted to prove his capabilities and started to modernize the system. The project took several centuries and Malacus had long since died when the world reached the technological progress of the rest of the empire but in the honor of their long dead leader the people of the system named their homeworld as Malacus Primus.
Meltrandt is a medium sized planet in the orbit closest to the systems star, Scwartchbaum. It is ttidally locked to the star, meaning that it always presents one side towards the sun and other side away from it. One side of the planet is boiling hot and other side freezingly cold but between the two extremes lies a zone of eternal twilight (or eternal dawn as the locals like to call it) where life can be found.

While the band of dawn is fairly narrow it can produce a large amount of food thanks to the eternal light that shines to it. This light can be augmented with large orbital mirrors that can simulate day/night cycle in the darker areas of the twilight zone.

Large ammounts of heavy metals can be mined from the sunward side, and frozen hydrocarbons from the dark side, these help to make Meltrandt a self sufficient in energy and industry needs and any surplus food can be shipped to the rest of the system.

The life on planet seems to share a very large portion of it's DNA structures with terrestial life so Magos Biologis of Adetus Mechanicus speculate that the planet was terraformed during the dar age of technology.

Current planetary governor is Her majesty Maerae Justina Cavor Malacus, the daughter and heir to the throne of the governor of the Malacus primus.
Malcus primus
Main world of the system, civilized world with population of 8 600 000 000 inhabitants. It has a fairly extensive space infrastructure and it has constructed several trade vessels and a few warhips for the Imperial fleet. It is a supricingly plesant world to live by (in Imperial standards that is). It has been always a tradition that the planetary governor of Malacus Primus rules over the entire system (apart from Orhum) and the governors of other planets and moons are relatives of the governor of Malacus primus.

Malacus Primus has a mild climate and normal seasons. There are still several unexplored ruins on the planets surface from the dark age of technology. A large amount of these sites are qurantined by adeptus mechanicus who are currently debating about what they should do with the sites.

Hogen is a moon of the Malacus primus. It has an extensive mining industry that supports the space infrastructure aroud the Malacus primus. Most ihabitants live in Garthum city. A large crater that has an ancient force dome generator from the dark age of technology that keeps the atmosphere and gravity in crater. Smaller versions of this same technology can be found from the most important ore processing facilities but most of the smaller setlements rely on solid domes to protect them from the cold void of space.
Space stations
There are three large space stations orbitting Malacus, they are numberred as 13, 21 and 29. it is speculated that originally there were at least 30 such large stations orbitting the planet but now only three remain. They are each huge cities in space with millions of inahbitants. Their main industry is ship building.
Orhum is an inhospitable penal world with a large schola progeninum. It is not administrated by Governor of Malacus primus since the world belongs to the eclessiarchy. Most of the prisoners of the world are relatives of executed heretics who try to earn a salvation for their sould by doing hard manual labour for the benefit of the undying God Emperor of mankind.

A large gas giant with two inhabited moons.
A volcanic moon of Izmak that has several habitation modules from dark age of technology that allows the inhabitants to live in a fairly good conditions despite the harshness of their homeworld. Main industries is mining.
An icy moon of Izmak that has a large hydrocarbon deposits that are mined for prometheum.
Navis Interficio

A mysterious space hulk that is aproaching the system. It is speculated that the current calm in warp is caused by an ancient ship of unkown origin at the heart of the hulk.