6. GTA San Andreas - Hot Coffee Mod
Before the Hot Coffee mod landed, Grand Theft Auto was already about as controversial as a game franchise could get, thanks to its hyper-violence, encouraged criminal activity and generally gleeful naughtiness. But then the infamous mod appeared, allowing players to access a removed mini-game in which CJ engages in sexual intercourse with his in-game girlfriend. The mini-game was disabled before the release of the game, but those careless naughty folk at Rockstar managed to leave all of the necessary pieces behind in the game's code, both on PC and console versions, to allow hackers to re-enable the mini-game and get their sordid little kicks from watching two game sprites bumping uglies. Naturally the world went mad with controversy and the game was reclassified as an adult game, forcing some retailers to pull it from shelves, before Rockstar released a new version, as well as an update for the old version that made accessing the mini-game impossible. Or nearly impossible, since clever modders still found a way in. Apparently in-game sex is far worse than running pedestrians over, shooting police officers and killing prostitutes...