Many of us who play Nier know that this game is a sequel/spinoff of another game series known as Drakengard. however alot of newcomers to the series are unaware of the story as to how this all began. so I'm writting this for those who are new to the series.

You've seen how the world of Nier is full of magical creatures, demons and such, but have you ever wondered where they all came from? how it all began? why civilization came to a crumbling end and now the characters are in a post apocalyptic wasteland?

For that answer, you need to go back several thousand years ago to a video game known as Drakengard.
https://www.youtube.com/watch?v=GwYYyXSya38

Drakengard is set in a fantasy medieval world with dragons, orges, goblins and such. but it had a very dark atmosphere. it was the Dark Souls of it's time except minus the undead curse. and instead of being instantly killed by everyone you encounter, the game actually had Dynasty Warrior style gameplay. meaning you were killing enemies by the hundreds.

How Drakengard is connected to Nier? you'll have to unlock the secret ending of the original Drakengard ending but here's a video that'll hopefully explain the events that soon lead into the dawn of the Nier universe.
https://www.youtube.com/watch?v=JE6n2KGbaZ0&t=323s

But if the video here was hard to follow, I'll try to explain the story the best I can. please correct me if I'm wrong any where because it's been a while since I last played any of the Drakengard games.

In the beginning, there was immortal young girls known as Intoners who could control magic through the use of song. think of them as Sirens except they did not eat people. the oldest of the Intoners, Zero, was on a mission to kill each of her sisters to prevent a disaster. in time the Intoners would begin to decay and become inhuman, posing a threat to humanity. Zero wanted to kill each of her sisters before this happens. however she succeeds but fails at the same time. her sister, One, cloned herself incase of the event that she is killed. One's clone kills Zero when her guard was down and moves on to form a cult known as The Watchers. One's clone then marries and has children.

Fast forward several generations later.

Two twins are born, Seere and Manah. these kids are the descendants of One's clone, so they secretly have the magical abilities of the Intoners. Seere is loved by his mother, but Manah is hated. Manah is beaten daily by her mother until the point she is left out in the woods to die. Manah is found by Imperial soldiers and taken in. when it is discovered Manah has the Intoner's power, she is made the new empress of the Empire. (Not sure what happened to the previous ruler though. probly killed because Manah is seen as divine and the current ruler isn't) through a unknown series of events, the Empire begins their campaign to search for the Seeds of Life so they can remake the world in their image. so almost all kingdoms across the land are invaded by the Empire to find each of the seeds. you play as Caim, the prince of possibly the last kingdom that has not fallen to the Empire yet. you gather whatever army is left over and prepare to defend the kingdom from the Empire's invasion, but there is just too many of them. think the Battle of Helms Deep from Lord of The Rings. (Except during the day instead of at night)

https://www.youtube.com/watch?v=gXC-jJhFaUI

You retreat to the castle where you find a dragon that has been chained to the ground. dragons are among the most powerful creatures in the world, and Caim knows this. so what does he do? he makes a deal with the dragon that if he releases her, they'll make a pact and fight the Empire together.

https://www.youtube.com/watch?v=2T2OBT4vXko
https://www.youtube.com/watch?v=sT4NIail0CY

Caim and the dragon successfully fend off the Empire together, however the Empire is still looking for the Seeds of Life and if they succeed, there won't be a world to save anymore. so Caim gathers what troops he has left and marches towards the Imperial Capital in a desperate attempt to kill the Empress and hopefully put a stop to all this. Caim and the dragon wreak total devastation to the Empire and encounter new friends along the way.

The game has multiple endings due to different timelines. so we'll focus on the path that leads to the dawn of the Nier universe.

Caim and his dragon fail to stop the Empire from breaking the seals that would give them access to each Seed. that's when they all realize these aren't the Seeds of Life, these are the Seeds of Destruction. portals begin to open in the sky and, I'm not kidding here, giant man eating babies start flooding out of them and eat people like the Titans from Attack on Titan.
https://www.youtube.com/watch?v=DN3P7aAEqqI

The Mother Beast, a giant woman with no physical features other than she is female, appears and begins devouring the whole world. but Seere preforms one last act to save us all.

https://www.youtube.com/watch?v=skLBop-zM-g
https://www.youtube.com/watch?v=6OPW-RdzStA

Caim pushes the giant mother through another portal, however you are pulled through too. both of you are spat out in another universe, a strange place called "Tokyo Japan" where you have one final battle with the giant mother. you successfully defeat her and prepare to leave... but... suddenly, you are hit from behind from something that explodes. you and your dragon fall from the sky in a ball of fire. as you and your dragon burn up and turn to ash, the magic held within both of your bodies is released into the atmosphere, as well as the Mother Beast's... and begins a series of events that will soon doom this new world you have entered...

A new disease is born and it begins to infect humans. it starts our rare, but then rapidly spreads putting the Black Plague to shame. Caim and his dragon are long dead at this point and their bodies have been moved to a lab for study. those who are immune to this disease survive this event, but all of civilization has crumbled.

A few years/decades later after Caim and Angelus were killed.
https://www.youtube.com/watch?v=2FHWEzrfZlE

And so that's how it all started. Nier is set in the aftermath of a war that almost destroyed two worlds ended by a prince riding on the back of a magic casting dragon. I can't remember where, but I remember reading lore of Nier and seeing a mention of "A red dragon falls from the sky" if you've played Drakengard then you know this was Caim and his dragon when they were killed by the Air Force.

I haven't played Nier: Automata yet but I'm going to soon. the game itself was pretty interesting but when I learned it was set thousands of years after Drakengard's secret ending, I was fully on board. whenever I played the first Nier and I was in a ruin from the old world, I actually went looking around to see if I could find a dragon's skeleton. but unfortunately I never did. I don't know what happened to Caim and Angelus's remains, or if they even still exist. it would be a nice easter egg to find. but again, I haven't played Automata yet so I don't know if there is any more mentions to Drakengard.

But what do you think? did I get anything wrong in the story? if so, please let me know and I'll make edits. again, I'm writing this for those who are new to the Nier series. you don't need to play Drakengard to understand Nier, but this game is still set hundreds of years after it. the biggest piece of proof is in the Recycled World DLC when you unlock weapons shaped into Angelus from Drakengard. A Fool's Lambet. this was my main sword out of my love for Drakengard. I just wish Drakengard would have a little more attention because Nier wouldn't exist without it.