According to the ESRB, this game contains: Blood and Gore, Violence
Parents don't have much to worry about with either title. Dual Hearts is completely harmless, and although Rygar does have some blood spurts when killing bugs or monstrous enemies, it's nothing that hasn't been done in a thousand other games before it. Neither game has any questionable language or sexual content.
Fans of Devil May Cry will definitely want to check out Rygar. It has none of the keyfetching or odd FPS action that Devil May Cry did, yet has all of the action. To be perfectly honest, if I had to pick just one, it would be Rygar.
Action-adventure gamers owe it to themselves to track down a copy of Dual Hearts. It's one of those unappreciated games that shows up in discussions years after it's disappeared. It does nearly everything right and is as solid as they come. It may be a bit cuter and less edgy than other titles out there, but the gameplay will win you over.
Deaf or Hard-of-Hearing gamers will have no problem with either game. Both offer full text throughout all dialogue and cutscenes.