The following story includes some major spoilers for the Ready Player One movie that are necessary to discuss its more adult moments.
Ready Player One is a movie full of fun pop culture and exciting video game action, but does that mean that it's ok for kids? While the vast majority of the film is likely to be perfectly fine for the vast majority of the audience, every kid is a little bit different and there are certainly a handful of moments that parents will likely want to consider before deciding if Ready Player One is ok for their kids.
The first point to discuss regarding Ready Player One is the language. The film is PG-13 and that rating allows for a certain level of profanity which the script fully takes advantage of. The use of "shit" and "asshole" is fairly free and frequent, in the way that it is used by teenagers in most movies. The PG-13 rating does also allow for the use of a single F-bomb, and it does get used. Near the end of the movie when a nameless bad guy character is confronted by a particular horror movie character who scares him into using the word.
And speaking of horror movie characters, there is a prolonged sequence in Ready Player One that is dedicated to a particularly popular horror movie of the 1980s. While the Ready Player One certainly holds on to its own PG-13 rating, the horror movie in question was originally rated-R. As such, there are some horror movie elements that might be a little too much for very young kids, even though they are toned down from the original for the most part. The movie in question also contains a scene with a naked woman. In Ready Player One, the scene is shot in such a way to prevent the camera from seeing anything that would make it a rated-R movie, though it is still clear in the film that the woman is naked.
As far as violence goes, while there s a lot of it, it's almost all of the video game variety. When one avatar gets killed by another, they explode into coins and items, rather than blood and guts, which can be collected by another character. It's actually specifically referenced by the creator of the OASIS in the film that he didn't want to include more blood in the game. It's also made clear in the movie that death within the game doesn't hurt anybody in reality, though many characters wear special suits that allow them to feel real pain when their character is hurt in the game.
The other thing the special suit does is allow characters to feel other sensations on their body. Everywhere. This leads to a particularly intimate dance sequence between two characters where a woman rubs up against a guy's groin. What the viewer sees is the suit light up at the crotch and the guy wearing it get a look of pleasure on his face.
All things considered, Ready Player One will likely be fine for most kids. Though, obviously, every kid is different, so depending on yours, there are some potential red flags here to consider.