Soldiers stalk through a ghostly, urban jungle of bombed-out buildings, approaching a pair of machine gun-toting enemies.

“Ok. I see two tangoes ahead. The closer one…take him out first,” orders a gravelly voice, as a German shepherd leaps onto one of the targets. Blood spurts from the fallen enemy, as he cries out in pain.

“Nice,” whispers the voice, as the soldier raises his machine gun to carefully sight the second of the two enemies.

The machine gun roars to life as the viewer watches the enemy mortally fall through a series of well-placed head shots.

If it all sounds like footage from an on-the-ground documentary out of the wars in Afghanistan, or Iraq, you would be wrong. The montage is just a 30-second sliver of a trailer for the soon-to-be published “Call of Duty: Ghosts,” the latest in an award-winning series of violent video games from Activison.

SPECIAL SERIES

Editor's Note: This is Part Two in a series exploring the connection between video games and violence.

Part One: 'Training simulation:' Mass killers often share obsession with violent video games

Part Two: 'Frag him:' With today's ultraviolent video games, how real is too real?

Part Three: 'Watch this:' How ultraviolent films differ from ultraviolent games

Part Four: 'Case study:' Has Grand Theft Auto finally grown up?

Indeed, spurred by technological advances that have pushed the envelope of processor speeds, games like “Call of Duty: Ghosts,” -- and their ilk -- offer their legions of fans an increasingly immersive and realistic experience.

But in an era when the horrors of war are brought so vividly to anyone inclined to purchase, say, an Xbox or Playstation, the question becomes, “How real is too real?” and what are the long-term and potentially lasting effects of repeatedly – hour-after-hour-after-hour – participating in such violent simulations?

The American Psychological Association has already noted that “when one combines all relevant empirical studies using meta-analytic techniques ... five separate effects emerge with considerable consistency. Violent video games are significantly associated with: increased aggressive behavior, thoughts and affect; increased physiological arousal and decreased prosocial (helping) behavior.”

And according to a study published in the journal of Youth Violence and Juvenile Justice in April 2013, “Violent video game playing is correlated with aggression…Based on data from a sample of institutionalized juvenile delinquents, behavioral and attitudinal measures relating to violent video game playing were associated with a composite measure of delinquency and a more specific measure of violent delinquency after controlling for the effects of screen time, years playing video games, age, sex, race, delinquency history and psychopathic personality traits. Violent video games are associated with anti-sociality.”

When it comes to video games, the industry has come a long way from Nintendo’s 1980s game “Duck Hunt,” in which players pointed a gun at screen and fired at crudely pixilated ducks flapping their way across a cloud-filled sky.

“Halo 4” was a top-selling, first-person shooter in 2012, a Microsoft-published simulation in which players stalk through a futuristic world armed with myriad weapons in a hunt for the next target on which to unleash their fantasy fury. Gameplay features a realistic lock-and-load function, where each time you fire your gun, the main character -- MasterChief -- jams another shell or cartridge into whatever is the current weapon of choice.

'Shrink your opponent and squash him with your foot. Freeze and shatter him. Attach explosives to his back. Roll a pipe bomb between his legs, or just frag him old-fashioned with a rocket.' — Website for violent "Duke Nukem" videogame

In “Gears of War: Judgment,” another Microsoft game, play is reminiscent of the epic first 15 minutes of the film “Saving Private Ryan,” as armor-clad soldiers troop through a dystopic landscape on the hunt for Locust forces. Tracer fire zips and someone screams out, “Hostiles!” The screen erupts with combat, as the player alternate between a shotgun and machine gun. With each successful blast, your target explodes into a red plume.

“This is my kind of fight,” the player’s character yells after a successful kill, adding, “Take no prisoners.”

“Hyper-realistic and intense combat,” gushes the game’s description on Microsoft’s webpage. “In Gears of War, the battlefield is a lethal place [and] to foolishly stand out in the open is to invite an untimely demise.”

Consider Duke Nukem, the main character of the 2011 hit, “Duke Nukem Forever,” which the game’s maker, 2K Games, proclaims on its official site as, “the steroidal One Man Army who never fails and always gets the babes.”

“Shrink your opponent and squash him with your foot,” reads the website. “Freeze and shatter him. Attach explosives to his back. Roll a pipe bomb between his legs, or just frag him old-fashioned with a rocket.”

And many games now employ so-called “cinematics” – movie-like sequences that advance the storyline and plot.

In “Resident Evil 6,” – an installment of the popular series from Capcom – your pistol-packing character stares down a zombie. “Stay right where you are!” he commands as the zombie menacingly advances.

“Mr. President…don’t make me do this,” your character warns one final time, before unleashing a single round at point-blank range into the side of the zombie’s head. Blood and whatnot explode everywhere.

As the video game action gets more realistic and more violent, evidence that it does indeed affect the behavior of players is increasing, according to Dr. Michael Brody, a University of Maryland adjunct professor who chairs the media committee for the American Academy of Child & Adolescent Psychiatry.

“There are all kinds of studies showing the connection between video game violence and aggressive acts and thoughts and affect,” Brody told FoxNews.com. “From my point of view, most video games and especially the successful ones, other than Madden Football, have to do with how many kills you make, and it pushes this general atmosphere of violence in this country… These video games where you win by shooting and killing…it’s definitely a public health problem.”

Of the games’ realism, Brody references chats he’s had with maimed veterans at Walter Reed Army Medical Center in Bethesda, Md., many of them young men steeped in the gaming culture before going off to fight in a real war.

“More than one openly volunteered how they felt when they were going to Iraq they were going into a video game,” he said. “I didn’t ask them. They volunteered the comparison. And the military uses these games for simulation of real-life experiences. The games are very realistic and that’s the difference between them and T.V. and film. In games, you are using a mouse or a joystick and you are interacting with the content and that makes it much easier to internalize the violent actions that are going on.”

Pamela Rutledge, director of the Media Psychology Research Center in Boston, disputes the idea that there is a link between aggression and interaction with violent video games – no matter what the level of realism.

“People seek a stimulus level that suits their needs,” Rutledge told FoxNews.com. “Some people play these games because it affords a certain level of arousal. That isn’t always a bad thing because, as you know, people perform better on a test if there is a slight level of stress. For a lot of kids, all of those games are about points and strategy and competition. And the realism heightens the experience and the attention of the player, but that doesn’t necessarily mean that it equates in their minds to killing a person.

“They’re already in the context that this is a game, and the fact that the game is realistic heightens the immersion, but that doesn’t change the fact that it is a game any more than playing ‘Battleship’ does with little plastic ships.”

But today’s violent games are well beyond little plastic ships.

In “Call of Duty: Black Ops 2,” released to great acclaim last year, a player begins in an armored vehicle with the U.S. president at their side. Los Angeles is under attack, and drones and helicopters fly overhead.

Suddenly, explosions scar the highway, and the president orders: “I want troops in the streets and these drones dealt with.”

She turns to you and asks, “What’s our next move?”

A moment later, you’re behind a flak cannon, blowing drones from the sky. Then you’re on the street, machine gun in hand, firing at will. Someone yells, “Be ready to move!” and the only thing that seems certain is that more intense action lies ahead.