I cannot, however, link you to any studies saying how videogames affect a person's violent tendencies or any studies saying they dumb us down. Because none say so.
Actually I've only ever come across one study that agrees with your opinion. But then again, that study says white kids get more violent by playing videogames while hispanic kids don't. So among dozens of scientific studies, that is the only one that agrees with what you're saying.
RE: Unleash a disease to kill all of humankind in Plague Inc and end up learning about viruses