RPG, anyone?

With the discovery of Warp space (an alternate dimension, composed entirely of energy instead of matter), mankind's expansion across the stars became rapid. We developed miraculous technology and weapons, and were as gods, pushing back alien threats, and colonising most of the galaxy. This period was known as the Dark Age of Technology, because man virtually sold his soul to science and technology. Nobody knew how high the price would eventually be.

Then came Psykers. Humans who for some reason developed the ability to manipulate Warp space with their minds. This supposedly amazing leap of evolution was disastrous for Mankind, because the Warp also has its inhabitants, malevolent beings who were born of man's hopes and fears, capable of traversing the link between the Warp and a psyker's mind. Many Psykers became possessed and laid waste to entire planets in their insanity and lack of knowledge of their abilities. the resulting chaos weakened human civilisation, allowing alien races once defeated to exact their revenge on their victors. Humanity fell apart, and most worlds degenerated into anarchy and near-stoneage culture. Only people with rigid self-discipline, or worlds where Psykers were vigorously suppressed, survived.

The arrival of the Emperor marked the return of mankind's former glory. A Psyker of immense power and self-control, He appeared on humanity's home planet of Terra and quickly united the world under his banner. He then started the Great Crusade of reconquest across the galaxy. He unlocked the secrets of life and created the Primarchs, near-godlike beings with incredible power, and the Space Marines, superhuman warriors bred from the genes of the Primarchs. With these mighty warriors the Emperor reconquered vast amounts of the galaxy and established the sacred Imperium of Man, the largest, most powerful domain in the galaxy today.

But the Emperor was betrayed. His first Primarch, and His most trusted general, the Warmaster Horus, was seduced by the foul gods of Chaos, rulers of Warp Space, and led to believe that he should be the rightful Emperor of humanity. He turned traitor along with fully half of the other Primarchs and their Space Marines, and the Imperium was consumed by civil war. The Emperor eventually slew the blasphemous traitor Horus in a mighty battle as Terra itself was besieged, but was Himself mortally wounded. The forces of Chaos retreated bitterly to the Eye of Terror, a breach in realspace where the Warp spews out energy and corruption, and time is meaningless. The technomages of the Adeptus Mechanicus built The golden Throne, a massive and incredible device, to preserve the Emperor's life so He could continue to rule. Mere mortals such as ourselves saw this as the Emperor's Ascension, and the creed of The Emperor Deified became the Imperium's religion.

This was ten thousand years ago. Today, it is the forty first milennium, and little has changed. Humanity is constantly at war with aliens, mutants, heretics, rebels, and the Forces of Chaos, the very same traitors who were defeated centuries ago. It is a time rife with superstition and suspicion, and every day is a struggle for survival where millions die in battle. Life is by necessity harsh, for the Imperium must be strong and strict if humanity is to survive. The death sentance, and worse, is common for many offences considered trivial milennia ago.

But often the Imperium cannot afford to execute criminals, such is the need for soldiers to keep its enemies at bay. For this reason the Penal Legions of the Imperial Guard were created. Here, criminals are sent to fight for the Imperium they betrayed, in the remote hope that by doing so they might redeem themselves. To disobey is certain death, but to fight offers a slim chance of survival. The Penal Legions are populated with some of the worst scum of the Emperor's domain. Murderers, black marketeers, heretics, petty thieves, and the occasional innocent who was in the wrong place at the wrong time.

People like you.