Just like violence in any other medium, there are times in gaming where certain bloody depictions cross the lines of taste. In many cases, these specific games aren't even that aesthetically explicit, but they go too far when the brutality itself is accompanied by a dark subject matter or delivered in a way that doesn't gel with the enjoyable, player-driven fun that most games strive for.
For the most part, video game violence can be pretty great. Being able to blow up, shoot, or stab an endless supply of faceless goons (or faceless human players) provides a cathartic joy like nothing else, and let's face it, for as much flack as it gets, digital claret is hardly the controversial topic the media has tried to make it out to be for years now. We've watched onscreen violence in movies for almost a century, so of course we're going to enjoy it just as much when we're put in charge of the wanton destruction ourselves.
That said, you won't be seeing the likes of Bulletstorm or Mortal Kombat here. While those games are some of the goriest the industry has ever seen, their violence is so ridiculous and so over the top that it's almost played for laughs.
Instead, these are the top instances where a game just got ugly. Either through sheer gratuitousness or because of underlying implications, the violent nature of these titles didn't make make you scream in excitement or laugh in disgust - they only left an unsavoury taste in your mouth that made you want switch the console off altogether.