Most of the time, you'll find yourself in the middle of massive firefights, bullets whizzing through the air, grenades going off way too close to you. These are the moments that separate the soldiers from the wimps, when quick tactical skills save lives, when total battlefield awareness and a fast trigger are the only things keeping you from taking a bullet.

Few games can put players into the heat and heart of battle like the "COD" games. Though the series has strayed from its World War II roots and into modern warfare for this fourth iteration, it's as stunning and exciting as ever.

"COD4" is a first-person shooter, a war game that does war well and paints a bloody picture of real battlefield experiences. You'll alternate between playing a member of the British Special Air Service and playing a U.S. Marine as you and your elite teams try to squelch volatile situations in, respectively, former Soviet states and the Mideast.

The game starts with a fun training mode that has you dropping onto a mock-up of a container ship. Your commander will shout instructions at you, and you'll have to pay attention to on-screen instructions so you can learn a variety of tricks beyond "point and shoot."

This first mission is like a showcase of everything the game can do. You'll experience the realistic sounds of guns firing, the stunning look of lightning flashing across the boat deck and the thrill of racing to escape a madly listing and rapidly sinking beast of a ship as water gushes in.

And then the introduction text rolls, and the intro music plays, and you realize you've just scratched the surface of the realistic experiences you'll encounter in "COD4."

Missions take you from dusty, crumbling Mideast towns to European farms. You'll be fighting indoors and outdoors, during daytime and nighttime (night vision comes in handy). Usually, you'll have to accomplish a variety of objectives in addition to your main goal. During an early mission as the Marine, for example, your team has to make its way to a stranded tank in the middle of a Mideast city, a la "Black Hawk Down."

"COD4" is merciless in terms of curve balls. You'll be in the middle of a firefight, ducking behind a block of cement as machine-gun fire rips into the ground in front of your cover, when some new dilemma will arise and your superiors will issue challenging new orders over the radio. About the only thing keeping you on track is a circle on your radar indicating your next rally or objective point.