One time I thought a great videogame would be called "Future Sociopath" and you'd start out as a toddler pulling wings off flies and progress from there. You know how one of the common childhood backgrounds to violent sociopaths is torturing and killing helpless creatures? Lack of empathy? Etc.? It would be like that. Perhaps you could even boost sales piggybacking off the success of Grand Theft Auto by implying it could easily be a prequel.
Yes, we all know that the link between childhood sadism towards animals and violent, dissociative adult behavior has been questioned, some say discredited, and that there's little hard diagnostic correlation to support the claim, but the idea is pretty well imbedded in our web of pop culture pop psychology notions - and isn't that half the whole fun of videogames to have some fun with our collective myths?
Also, if we can get young people to play the game it could keep them from doing it for real. Sometimes, you really don't want Johnny to go play outside.