Franchises often choose to expand with direct sequels or prequels, but sometimes there can be spin-offs which are a bit more on the messy side. The Nier games were born from a classic fantasy series called Drakengard, and those who want to understand how they all connect will have to do a deep dive into some complicated but interesting lore.
Unlike most linear stories, video game properties (especially those made by Square Enix) often take a wildly different approach. The first in the Drakengard series is technically the one that leads into Nier, but that story will make more sense with the context from Drakengard 3.
The Timeline of the Drakengard Series
Drakengard 3 took place in the fantasy setting of Cathedral City and its surroundings. The player controlled Zero, who along with her intoner sisters, could control magic through song. After Zero discovered that the intoners' power came from an evil flower who wanted to destroy humanity, she set out to kill her sisters in an effort to stop this plan from reaching fruition. By the end of Drakengard 3 she completed her mission and destroyed all the intoners- including herself.
Of course, things are never that easy, as one of the sisters created a clone of herself, who went on to have children which possessed the intoners' powers. These children would create a cult known as The Watchers. The story of Drakengard began generations later when a hero named Caim fought against The Watchers, who sought out the seeds of destruction. These seeds could be put together to create a portal to another dimension and summon an evil being to destroy humanity. Each seed was stored inside one of the various kingdoms, and The Watchers' powerful empire had conquered all but one; the one Caim fought for. Though Caim fought valiantly with his dragon companion's help, The Watchers ultimately acquired all the seeds and opened the portal.
How One of Drakengard's Potential Endings Sets Up Nier
One of Drakengard's possible endings showed a gigantic demonic being emerge through the portal. Caim used the seeds to open another portal and fought the creature through it. This brought them to 2003 Tokyo, where Caim and the dragon were stranded. Although the duo successfully destroyed the evil creature, Tokyo's government saw them as a threat, using their air force to kill them both.
Their deaths spread their magical essence across the land, causing a devastating disease for the humans who live there. This disease annihilated most of the human race and set up the story for Nier, where the protagonist fought to save himself and his sister from the fallout in this post-apocalyptic land. That, in turn, leads to the most recent entry in the series, Nier: Automata, which is set thousands of years after Nier. Although an alternate ending connects Drakengard and Nier, the main stories and characters have basically nothing to do with each other. Some games are spin-offs, but this franchise has spun way off.