What makes a game controversial is going to come down to individual user's definitions. But I am trying to think of games that offered a quality product AND possibly took things a little too far. There are 1000 games that are grotesque, pornographic, hyper violent, and more. But I think those ones shouldn't count. I'd rather think of games that had something to offer (whether that be artistically, or through gameplay) that made you want to keep playing them in spite of being uncomfortable or offensive.
Some that come to mind are Pico’s School, Ray, the entire Assassin series/craze, The Suicide Bomber Game, Dead baby dressup, Johnny rocketfingers, Frank’s adventure, Clubby the seal, Whack your boss, Little red riding ho, Pimp’s quest, and maybe even Don’t shit your pants?
I'm not confident all of those were controversial, and many were instead maybe just a little edgy. But I don't think I grew up seeking out the seediest, most over-the-top games. So I'm hoping that you guys can think of some more to share and discuss!
GAH!