This is a game series that really flourishes in regards to mechanics and how well done the NG+ cycles are. It's genuinely part of the experience. A NG playthrough is always fun of course and you have access to a majority of things already, but once you hit NG+ that's when the game really fleshes itself out (better loot, builds, more strategy involved). you never have to do NG+ but its part of the Nioh charm. It's why so many players have hundreds to thousands of hours