You are too narrow-minded, my friend. You didn't even pose a good argument for halfcentaur. You just make an additional ridiculous example. I know you are not a gamer but you are not also looking at a deeper sense here.
So what if the game is about killing other heroes for you to win? That doesn't mean that the player who controls the hero can be surely considered killers. It's not the game that should be blamed here. It's the person himself, the people he associates with, the environment he lives and the parents' way of raising him.
I admit I play violent games like this one - Dota 2 and other games like Call of Duty, Grand Theft Auto, Need for Speed: Most Wanted, Assassin's Creed and any other violent game that you could think of. But I don't think it influences me to do harmful things to my fellowmen, rather it teaches me how to think critically and quickly to solve certain problems - excluding killing other people.
In a nutshell, widen how you think about games and about life in general.