On a related note, I'm a big fan of the BBFC (British Board of Film Classification, though they also do some videogames) website, from which you can search any movie title and get a detailed, concise but entirely objective appraisal of the reasons it earned its particular age certificate, possible areas of concern etc. Here's what they had to say about Nier:
"NIER is an action adventure role-playing game (RPG) for the Microsoft Xbox 360 and Sony PlayStation 3 platforms. Played from the third person perspective, the game includes 'hack and slash' and problem solving elements. The game begins in 2049 in a post-apocalyptic city and the player assumes the identity of Nier, the father of a young daughter who is sick with the Black Scrawl virus. Nier, who must find a cure for the viral infection, is transported 1300 years into the future into a distinctly medieval-looking environment. He teams up with a magical talking book, a scantily clad foul-mouthed young woman and a strange skeleton-like creature. The game was passed 15 for strong language and bloody violence.
BBFC Guidelines at 15 state that 'there may be frequent use of strong language (for example 'fuck')'. The game includes several uses of that particular term, in all cases uttered by Kain, a young female character.
The Guidelines at '15' also state that 'violence may be strong but should not dwell on the infliction of pain or injury. The strongest gory images are unlikely to be acceptable. Strong sadistic or sexualised violence is also unlikely to be acceptable'. During the course of the game the player will kill or destroy hundreds of 'shades' (shadowy monsters), boss monsters, wolves and robots. Killing 'shades' or monsters with an iron bar or a sword, etc produces copious blood spurts but no injury detail. Blood and corpses disappear from the screen after a few seconds and it does not appear possible to inflict any form of post-mortem injury or damage. Moreover, it is not possible to injure or kill innocent bystanders, nor indeed any human characters. In addition to using conventional weapons, Nier can zap opponents using the magical powers offered by the talking book. Some of the cut scenes include blood but there is no particular dwelling on the infliction of pain or injury and at no stage in the game are there any very strong gory images that challenge a '15'. In one cut scene Kain is impaled on a giant metal spike. A large spurt of blood shoots from her back and she is then seen to be lying in a large pool of blood. There is, however, no injury detail and she appears to make a full recovery. In another cut scene there is a spurt of blood as Nier pulls a blade from his shoulder. Again there is no injury detail. There is no sadistic or sexualised violence in the game and, overall, the violence falls comfortably within '15' classification category parameters.
Although Kain is dressed throughout in skimpy knickers and a short negligee, the game includes no nudity or sexual activity."
See that? Just the facts and possible areas for parental concern, no judgement.