6 horrifyingly violent video games to keep your kids away from

Like books, movies, TV shows, and any other form of popular entertainment, video games run a wide gamut of child-appropriateness: from "safe as Mario" to "do not let your kid anywhere near that gore-fest!" Some of these might be OK for older teens or adults who enjoy playing bloody action titles (they're all rated Mature by the Entertainment Software Rating Board).

But we talked with Eugene Beresin, M.D., Professor of Psychology, Harvard Medical School, and Executive Director of the Clay Center for Young Healthy Minds at Massachusetts General Hospital. Mass General studied the correlation between violent video game play and behavior in 7th and 8th graders.

"Most parents don't know the content of the games their children are playing," he said. While the study showed that the majority of kids weren't adversely affected by violent gameplay, around five percent did show a correlation between aggressive behavior and the number of hours they played violent games. "If your kid has problems with aggression or depression, then limiting their gameplay is a good idea."

So if any of the following appear on young children's gift lists, cross them out immediately with a black Sharpie. Instead, check out our picks for "Six great games for kids this holiday season."

Assassin’s Creed 4: Black Flag, $60
Available for PC, PlayStation 4, Xbox One
Why the Mature ESRB rating?
Blood, sexual themes, strong language, use of alcohol, violence

The Assassin’s Creed games have grown into one of the most popular series in gaming. The overall plot: Desmond, the main character, is connected to a machine that lets him relive the events of his ancestors' lives. And his ancestors just happen to be some of the most infamous assassins in history.

In this newest entry, players take on the character of Edward Kenway, a pirate who engages in large- and small-scale battles. The focus, as the title implies, is on assassination. Players choose from many different weapons to kill enemies, though the series' trademark weapon is the Hidden Blade, which comes from a device worn on the wrist. Assassin’s Creed IV has been well received, with a lot of praise for the large open world and the new naval battle system. But it's rated Mature for a reason.

Deadpool, $40
Available for PC, PlayStation 3, Xbox 360
Why the Mature ESRB rating?
Blood and gore, intense violence, mature humor, sexual content, strong language

Anyone who's familiar with the popular Marvel Comics character Deadpool should know exactly what to expect from this game. He may look kind of like a cross between Spider-man and Wolverine, but he behaves more like a combination of Scarface and Spongebob, and all of his glowing personality is on display in the game.

Deadpool is as obsessed with mutilating the anatomy of his enemies as he is with admiring the female anatomy. Players use his arsenal of swords and guns to slice and shoot their way through hordes of enemies. This type of glorified and apologetic violence may be a lot of fun for adults, but it isn't appropriate for children. Don't be fooled by the superhero mask!

Grand Theft Auto V, $60
Available for PS3, Xbox 360
Why the Mature ESRB rating?
Blood and gore, intense violence, mature humor, nudity, strong language, strong sexual content, use of drugs and alcohol

Grand Theft Auto is generally the first thing that comes to mind when people discuss violent video games. The newest entry into the series, Grand Theft Auto V, takes the open-world gameplay and the violence to the next level.

The GTA games have always encouraged the player to steal vehicles by dragging the driver out of the car. Beating civilians to death on the street earns cash that players can use to pay for more expensive ways of causing destruction. One controversial mission in the game, called "By the Book," has the player take control of a graphic torture scene. Obviously, none of this content is appropriate for children.

Find more news, reviews, tips, and trends in our guide to video games, consoles, and tech toys.

Ryse: Son of Rome, $60
Available for Xbox One
Why the Mature ESRB rating?
Blood and Gore, Intense Violence, Partial Nudity, Sexual Content, Strong Language

One of the launch titles for the Xbox One, Ryse: Son of Rome has incredibly realistic graphics—which also, of course, add to the realism of the violence.

You play as a Roman warrior, Marius Titus. After you damage an enemy enough, you can perform your choice of executions. These range from slitting throats to stomping on enemies' skulls. This type of vengeance can be grimly satisfying, after a tough battle, for grownup gamers, but it's way too gruesome for kids.

Saints Row IV, $47 to $50
Available for PC, PlayStation 3, Xbox 360
Why the Mature ESRB rating?
Blood, intense violence, partial nudity, sexual content, strong language, use of drugs

The Saints Row series has been considered by many to be a clone of Grand Theft Auto: It contains similar open-world environments and violence-glorifying gameplay. In Saints Row IV, players create their version of the President, who is defending the planet from an alien invasion.

This character is pulled into a "Matrix"-like simulation where he can use superpowers to brutally pummel his enemies. And missions called "Insurance Fraud" encourage players to throw their character in front of as many vehicles as possible to collect insurance money. Adults only, please!

The Last of Us, $60
Available for PlayStation 3
Why the Mature ESRB rating?
Blood and gore, intense violence, sexual themes, strong language

The Last of Us falls into the post-apocalyptic genre: 20 years ago, a virus appeared that causes humans to mutate into zombie-like creatures. Players take on the character of Joel, who has been tasked to deliver 14-year-old Ellie to a group called the Fireflies. In travels between Texas and Utah, Joel does battle with the infected and bandits.

Some of the attacks in the game are very gritty, as Joel strangles enemies or brutally beats them to death. And in one scene, Ellie gets into a knife fight with an older man; she wins by hacking him to death with a machete. The violence in this game, while extreme, is a bit more justified than in some of the others: These are people who are trying to survive in a different world. That doesn't mean it won't cause young ones some very bad dreams.

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