You should start with Nier: Automata. It is technically the sequel to Nier Replicant, but it builds upon the original game in every way. The combat is faster and more pleasurable, the story is easier to follow, and its alternate playthroughs change the game in dramatic ways.
It's not hard. You are able to not only grind levels but also upgrade your weapons and stats easy. Only the bosses can be hard but that's to expected but by no means does it ever feel unfair or a pain to play. Enjoy the game!
Yoko Taro talked about the issue defined "open-world fatigue" and how he gave players the sensation of freedom in NieR and NieR: Automata. Open-world games have vast maps, many quests, and lots of other things to do like crafting and more.
Nier Replicant is the prequel to Nier Automata, not the sequel. Replicant is a remaster of Nier, which was released in 2010. While the game saw modest success when it first debuted, it wasn't until Nier Automata released in 2017 that the series gained wide popularity.
We conclude that the controller is definitely an optimal tool for playing Automate, although it is quite playable on the keyboard with certain challenges and limitations.
Score. Nier: Automata is a great game for action, anime and science fiction fans. I really enjoyed playing (most of) it. But as it does a lot of things incredibly, it also fails in a few others.
TL;DR: No, you don't have to play Drakengard 3 prior to NieR:Gestalt/Replicant, although this comes from someone who has only watched playthroughs of these games. Actually, I found Drakengard 3 to be unfitting to Replicant and Automata due to its blatant vulgarity and obvious lewdness.
With that in mind, getting to Ending A will take around 15-17 hours, assuming you've done a healthy amount of sub-quests along the way. That'll take you to credits for the first time, but it's far from over at that point. Wrapping up all five endings takes closer to 30-35 hours.
If you have the choice, go for PS4. I've played on both, I had no issues on PC with the FAR mod, and it looks a lot better.
NieR Automata's PC version was infamously bad, so much so that the game still requires user-created mods to get the game to run well on PC. Even then, the game still has bugs and performance issues. While fan fixes will get the game running today, Square Enix needs to address the game's many issues with patches.
It was clear Nier was made on a lower budget than the popular action games it was up against at the time. But it was also fascinating. The story and characters were compelling, bizarre, and deeply tragic. This became one of Nier's best and enduring qualities.
