The worry, here, is whether a small child understands that there's a big difference between an app and fake blood, and a real saw. Because it would be tragic if he tried it with a real saw.

I think kids are generally smart enough - if you explain it to them - to grasp that. My generation grew up with some pretty vile cartoon violence, and it didn't turn us all into little psychopaths. (Some viewers had more empathy than others - I'm still rooting for the coyote, poor fool, or for the Trix rabbit to get a taste of a cereal he'll probably hate but worked so hard for so long just to try.)