According to the ESRB, this game contains: Blood and Gore, Violence
Parents should be aware that the game revolves around swordplay, and where there are blades to be swung, profuse splashes of red stuff are sure to follow. Needless to say, heavy doses of violent action are constantly present throughout the game, but otherwise there's nothing to be overly concerned about.
Gamers in general should be aware that while Onimusha is eye-catching, the gameplay is a distilled version of the Resident Evil formula, pure and simple. There's nothing fresh or particularly innovative about it, so if you're someone who is tired of the same old game repackaged for yet another sequel, you might want to rent it first. Another reason to be cautious of spending $50 on it is the games short length of approximately five hours.
Hardcore survival-horror fans will eat this game up since it's nothing but more of the same, save for samurais and swordplay taking the place of bioengineering and firearms. The puzzles, oddly-shaped keys and all the other tired conventions of the genre are all here in their full glory to either excite or bore, depending on the gamer.
Fans of Eastern themes will appreciate one of the first games to my knowledge (besides Shenmue) which visually depicts Japanese people extremely realistically instead of as racial caricatures or neon-haired anime cartoons, as well as the architecture and general atmosphere of a demonically distorted feudal-era Japan.
Deaf and Hard of Hearing gamers are granted a special treat, having the choice between English or Japanese subtitles in addition to the games choice of language during the voiceovers.