In the mid 1500s, the demons revealed themselves to the world. All across the Earth, demons of all different kinds attacked major cities and countries, each having their own unique skills. The most powerful of all demons being the Oni. Ordinary weaponry could not harm them, thus most of civilization fell. However there was one place humanity stayed strong: Japan. Due to the strong spiritual energy spread throughout the country, the people have been hunting demons down for years. The people discovered long ago that the way to defeat demons was to use weapons made from demons themselves. Thus, a secret society of demon hunters was born. Utilizing their special weaponry, humanity pushed back the demons. Then the Oni deployed their own secret weapon. Opening portals to who knows where, these portals released Miasma, a spirtual energy beneficial to demons but harmful to humans unto the world. Humanity was pushed back once more as the Oni hunted them down and took over demon society. The age of demons had begun.
The early 1600s, humanity was nearing extinction. The spread of Miasma was too great, forcing the people who remained to retreat to secluded villages. Special Priests and Priestesses were able to set up barriers which kept demons out, and special purifying stones that pushed back the Miasma a bit. But sometimes there was too much for either to handle. Then a miracle came. There was a scientist who studied an ancient civilization that fought the demons. She was able to reverse engineer their technology and create a device known as the Demon Hand. According to her," The Miasma holes will never stop pouring out Miasma. There is no hope in pushing it back as long as they remain open. That's where my device comes in. It was a demon, more specifically an Oni, who opened them in the first place. It only makes sense they can also choose to close it. The Demon Hand is essentially just that, the hand of a demon. Like our own armor and weapons, it utilizes a demon's own essence against them. The Miasma holes aren't alive, therefore they won't be able to tell the difference between a real and fake demon. We finally have our key to victory." The Demon Hand truly was humanity's key to victory. In addition to closing up Miasma holes, the Demon Hands could be used as grappling hooks and could even temporarily change form into a weapon. They were great for cutting off demon limbs, and could even prevent certain limbs from regenerating. The greatest surprise came in the ability to extract Mitama. The Mitama are the spirits of people from all across history who were devoured by the Oni. Bonding with those that freed them, Mitama granted people powers and abilities never seen before. The demons were now being pushed back.
It took nearly 300 years, but by the beginning of the 1900s, humanity reigned supreme once more. Spreading the technology developed in Japan, more and more people began to fight back against the demons. Technology just kept improving over those 300 years, allowing for faster transportation and such. Even though there are places the demons remain strong, humanity can now rebuild. Due to the destruction brought by the demons, the majority of human art and culture has unfortunately been lost. Because they managed to keep things preserved, the majority of human has adopted a very Japanese like culture. There are exceptions though, such as places that contain european knights from medieval times. Modern technology such as cars, phones, television, radios, modern medicine, and even computers exist thanks to the reverse engineering of the Precursor's, the ancient civilization, technology. Despite all this, humanity still remains very traditional culturally. The age of demons had ended, and the age of reclamation had begun.
In the 1950s, humanity created the first interstellar exploration ship. The goal was to find other worlds to colonize in case the demons ever took over the Earth again, and humanity failed to fight back.
By the 1980s humankind has established thriving colonies on both the moon and Mars. Thanks to humanity's now natural spirutual abilities, they were able to teraform both, allowing for unique life to sprout forth on them. Chang'e, goddess of the moon, was discovered and now runs the lunar colonies. In fact, more and more gods of legends started to reveal themselves. According to them, the Oni had sealed them away long ago but thanks to humanity pushing them back and closing the Miasma holes, they were once again free. There was a lot of mixed feelings about all this.
A decade later, things continue to advance. The gods have reestablished themselves, forming a council of sorts. Although some believe they should rule over humanity as they have before, most agreed they would instead work alongside them. With the advancements humans have made in their absence, they believed they could help the gods achieve even greater heights, but only in working with them. The gods told humanity this, and the Alliance of Earth was born
In 2014, humanity has successfully replicated Machina. Machina are machines that were originally made by the Precursors. Using spiritual energy, the Machina could think and act on their own. They are not classified as AIs though. They are actual living beings with souls. The amount of spiritual energy determines how sentient the Machina is. Ones with low amounts can barely think and are used as servants and workers. Those with higher spiritual energies are given the same rights as people and are generally considered the ones truly alive. There are even cases of a person having their spirit transferred into a Machina.
In 2035, ruins are found on Mars. They are first believed to have belonged to the Precursors, but further investigation proved that to be false. They belonged to an alien race called the Protheans. At first, people believed this might help advance technology, but the gods found out it was actually a trap. The gods combined their powers with that of several priests and priestesses in order to look into the past. What they found was that the technology actually belonged to a machine race known as the Reapers. They left this technology behind in order to control the technologic advancements of sentient races, make them a bit stagnant, and easily wipe them out. What made it worse was that it was also discovered the demons use the Reapers. Not known to the Reapers, the demons would hide on a world and cause a bit of chaos, then use the mass extinction events to consume the souls of all who were killed, growing stronger each time the Reapers came. The demons would sometimes even secretly help the Reapers by showing races Mass Effect technology. Everyone present for these visions declared now and then," No More!" The gods completely obliterated the Prothean ruins, not leaving a single trace behind. Everyone, both offcial and civilian, was told of everything they discovered. How those ruins were actually a trap of both the demons and the Reapers. They would not fall for it as so many have before. The Alliance now had a new goal, end the cycle once and for all.
Once the demons found out their plans were revealed, they decided a different course of action was needed. It took over a year, but the demons had a new plan. Using their methods of travel, several demons left Earth in order to establish themselves on other worlds and grow in numbers and power. The Alliance caught wind of this and tried to stop them, only to be met with failure. Although a lot of demons still remained on Earth, so many had ventured off into the unknown.
In 2053 the Sol System's Mass Effect relay is discovered. Knowing the truth of it, the Relay was torn apart for resources. All eezo was disposed of as humanity treats it as if it was cursed.
In 2079, the first non-eezo form of FTL is developed, allowing acess to systems outside the Relay Network.
2083, human colonies have been established on other planets. They quickly thrive thanks to help from minor gods.
In 2099, demons start appearing on colony worlds. Two military groups are developed in order to counter: the Guards and the Samurai. It is the job of the Guards to do essentially just that. Demons are known to be able to sneak through defenses and attempt sabotage. The Guards address these situations, killing any demons that manage to get through. The Samurai are the offensive division. They charge at attacking demons and intercept them. Casualty rate is a bit higher for Samurai, but is generally considered more glorious. There also exists several freelance demon slayers who wander from planet to planet.
In 2134, the Armor Machina is created. The Armor Machina is a 15 meter tall humanoid vehicle designed to counter warships and large demons. AMs are highly customizable to allow adaptation to different environments. They also require two pilots in order to operate. One is to regulate the flow of the spiritual energy, the other to control the AM's movements. Both are needed for it to have enough energy to run. Older and/or failed models are used in construction and other tasks. Although possible for freelance slayers to acquire, it is very expensive and freelancers usually have to get one as a reward.
2157, contact with the Turians is made.