When Steven Spielberg collaborated on the creation of the first “Medal of Honor” game in 1999, he wanted to create an interactive analog to Saving Private Ryan.

It was something fresh and intense: an attempt to use all the tricks of game design — immersive sound, bobbing motion, layers of action, goal-oriented gameplay — to put you inside a war movie.

Activision and Infinity Ward followed with the “Call of Duty” series in 2003. Over the course of three games, “Call of Duty” developed the World War II theme while maintaining a “Teen” rating thanks to a minimal use of blood and foul language.

Multiplayer gameplay made the series popular with young gamers, and extensive historical context and period footage made them popular with parents. This was the way a new generation of boys “played war.”

Things started to shift with “Call of Duty 4: Modern Warfare.” More intense modern firefights, increased blood and more mature language was used to evoke the modern battlefield, earning a “Mature” rating. Fair enough. It was a strong game, with heroic characters and a terrific multiplayer mode.

When the series returned to World War II for “Call of Duty: World at War,” the “Mature” rating came with it. The blood and gore increased, and if parents happened to see an early scene of torture and murder, they might have wondered just what they’d let in their home.

But they didn’t. “Call of Duty” was a “safe” first-person shooter, wasn’t it? That “Mature” rating? Just a little bit more blood, their kids assured them.

And now we come to “Call of Duty: Modern Warfare 2,” the most intensely hyped game of the season, opening with the biggest launch of any entertainment product in history: It hauled in $310 million in 24 hours.

Now parents are faced with a game that turns all the dials up to 11 and blows out the speakers. The gameplay is a nonstop assault on the senses: gunfire, explosions, screams, blood spattering the screen, flying gore and convulsing bodies. This is to say nothing of the storyline and context, which are nihilistic, brutal, cynical, anti-American, antiheroic and antimilitary.

Bit by bit, parents were betrayed. They justified incremental increases in mature content by saying, “Well, it’s just a little bit more intense” until finally they walk in on their 11-year-old and witness this:

A group of men enter an airport where civilians are peacefully waiting for their flights. The image on the screen is the perspective of your character, gun in hand. Calmly, slowly, methodically, the men walk through two entire levels of the airport mowing down civilians. They scream, run and drag their wounded bodies through smears of their own blood until someone, perhaps you, puts a bullet in their heads. Scores of unarmed people are mowed down. At the very end, your character is shot in the head, left staring lifelessly at the ceiling as blood pools around him.

It is one of the ugliest and most disturbing things I have ever seen in a mainstream game. It leaves the gamer feeling brutalized and violated, or at least it should if he hasn’t already been numbed by a steady diet of violence.

The designers, no doubt, think they’re being very bold and mature in grinding their fans’ noses in the muck, but it’s hard to imagine a more complete betrayal of a franchise. Is the cold-blooded massacre of innocent civilians really an experience on the emotional spectrum that we need not only witness, but simulate?

The designers’ defense is that they warn you about a “disturbing” mission and allow you to skip it, but this is rank nonsense. People are so immune to “controversial” content warnings that, without specifics, they are unlikely to bypass part of the game. In fact, for the young people who most desperately need to skip this sequence, such a warning is pure catnip.

The rest of “Modern Warfare” never quite matches that level of ugly nihilism, but it still wallows in moral relativism. The airport sequence is there to tell you, quite plainly, that the designers see no difference between terrorists and U.S. Army Rangers. There are no good guys, only competing ideologies. This is a military game that hates the military, with Americans depicted as either dim grunts or lunatic cowboys with no regard for human life.

No doubt, the designers think they’re being very daring and mature: so daring that the bad guys are “Russian nationalists,” not jihadists. If Infinity Ward was really so committed to depicting the moral ambiguities and horrors of the modern battlefield, then “Modern Warfare 2” wouldn’t be so politically correct.

And for all this, the gameplay really isn’t all that spectacular. “Modern Warfare 2” is actually a pretty middling shooter with a decent multiplayer component. There’s no covering fire, enemy units seem to pop out of nowhere without any logic or consistency, and overwhelming opposition takes the place of sophisticated AI. The storyline is such gibberish that it’s hard to figure out what’s going on, and levels seem to have no clear purpose. You simply move forward on a roughly predetermined path until one level ends and the next begins. Multiplayer remains a strength of the series and will keep the game alive long after its execrable narrative campaign is forgotten.

If “Modern Warfare 2” proves anything, it’s that parents need to pay attention to ratings. They are there for a reason. If you wouldn’t let your children see an R-rated movie, then don’t let them play an M-rated game unless you have a comprehensive, direct understanding of its content. Eternal vigilance is the price of parenthood.

Thomas L. McDonald is editor-at-large

of Games magazine and a catechist

in the Diocese of Trenton, New Jersey.