The whole premise of this topic is failed logic...
Games like Dark Souls, Dragon Age, DarkSiders 2, Rayman Origins, Any fighting, Racing, Sports game, any Mario game, and plenty of more have absolutely no guns, and they still sell well and are fun. It has absolutely nothing to do with guns.
And lets talk about older games, where instead of shooting someone you jumped on their head, pushed enemies into lava, pounded them with a hammer, kicked them off a cliff or other high point, or even stabbed them with a knife.
And like someone already mentioned...games of past generations were just as repetitive or guilty of clone-syndrome. Just go back to the NES or SNES days, where 9 out of 10 games were a platform side-scroller.
Yeah, only games with guns are violent &/or not fun (innovative).
I can tell some of you haven't been playing video-games for very long.