I didn't play the NieR games so I cannot comment on how accurate it is to the original game or something like that. I just came across the anime without prior knowledge, and it was just, amazing. Loved 2B and 9S's relation and how they were together in the end, along with the show's concept of consciousness in robots. The show also explains stuff nicely when needed so I never really got confused with the story. Give it a shot!
Maybe a slight spoiler:
(Adam got what he deserved in the end, I don't wanna see anyone feeling bad for him he did it to himself)