Pedophilia is considered a psychiatric disorder in which in adult has a sexual attraction towards prepubescent children; it could also lead to child molestation. Pedophilia isn't very common in video games but has made some appearances.
In one case, Cole Phelps responds to a call regarding a lurker at a high school. The lurker is seen spying on two high school girls as they are about to head home, Phelps arrests the creep and later interrogates him regarding a murder.
Another case has the player finding a 12 year-old girl naked in a suspect's bed, while searching their apartment.
Grand Theft Auto IV
GTA IV has an in-game internet with dozens of websites that the player can visit. One such site is www.littlelacysurprisepageant.com, which is advertised on the in-game radio stations as a beauty pageant featuring little girls wearing sexy lingerie. If the player visits the website, it is revealed that it's actually an elaborate trap for pedophiles, and they are presented with a message from the LCPD saying that they've taken down the site and that the IP address has been logged. Upon exiting the computer, the player will have a 5-star wanted level.
The character Leonard is a pedophile who inadvertently escaped a tragedy that claimed his family while he was away, engaging in an act of child molestation. He blames himself for the deaths of his brothers. His weakness eventually leads him into being forced into a pact with Faerie that leaves him blind. Similar to other sexually controversial character backgrounds in the game, overt references to Leonard's pedophilia were removed from the North American version of Drakengard.
The character of Sweet Tooth in the Twisted Metal series is a known child molester that also kills the children, though rather than doing it out of motivation of genuine pedophilic attraction, Sweet Tooth is just a psychopath who revels in the suffering of others, and rape is just another tool to reach that end.
The most controversial game involving this concept was Rapelay, an eroge revolving around rape. The player controls a stalker that can rape a mother and her two daughters, one of which appears to be a prepubescent child. Despite never being released outside of Japan, the game sparked an international outcry that led to the publisher Illusion banning the game.