NieR is a very odd beast of a game. Blending various elements together that don’t normally mesh well (wacky story, gameplay that changes frequently and more) allowed the title to become a classic for many gamers during the PS3/360 generation. With the recent release of NieR Automata on the PlayStation 4 (and coming out on the PC in the future), YouTube content creator Super Bunnyhop put out a video explaining the game.
This includes backstory of the game’s world and setting among other elements (gameplay, lore from prior games in the series, etc). I really enjoyed watching this video, as I became more informed about this series and it got me excited for Automata.