Wow, just wow! If you've played through COD4's main campaign then you will know exactly where I'm coming from. Never before has a game managed to give me so many heart-in-my-mouth moments, nor managed to elicit the odd "*^%$ yeah!” from my mouth. In simple terms, COD4 is pure class. From the moment you fire the game up you'll be treated to one of the most intense, fluid and expertly paced shooters ever created.

The first mission is a great example. You start off in a fairly typical training situation, but it's not long before you're thrown into a mission that sees you infiltrating a ship at sea, taking out the bad guys and ultimately racing to escape the tanker as it starts to sink. It's a fantastic introduction to the game and the action never lets up from start to finish.

Infinity Ward wants you to know that they make the best war games out; this is apparent in the balls-to-the-wall structure of COD4. Almost every type of modern war situation is thrown at the player, to the point where it becomes almost like sensory overload. Not only are the game's graphics some of the best that we've ever seen, it's the way that the game paces you that really impresses. You never really feel like you're being forced to play through a linear adventure. You WANT to storm that house; you WANT to keep on pushing through the town to take out the target; ultimately, you WANT to be the kick-arse hero who takes on the terrorist army and saves the day.

Without spoiling things too much, this last desire might be a bit harder than you think. You see, COD4 excels in keeping you hanging when it comes to what can happen to main characters. Hell, in the intro to the game you're treated to the first-person experience of a deposed Middle Eastern leader being executed by insurgent rebel terrorists (wow, what a tagline to have). In fact, I can't think of another first person shooter that has succeeded in putting you so close to the action, actually in the boots of people dying or being betrayed. It certainly helps to connect you to the story, even if the story itself involves a somewhat predictable ‘nukes-will-destroy-America' situation.

COD4's campaign is fairly evenly split between two main characters, which is a bit different to the previous Call of Duty games and their American/British/Russian approach. The two main characters in this game are Sergeant Paul Jackson of the United States Marine Corps 1st Force Recon, and Sergeant John "Soap" MacTavish of the 22nd SAS Regiment. Missions themselves are fairly evenly split between Middle Eastern and Russian locations, with an intertwining story involving Russian Ultranationalist party leader Imran Zakhaev. He's a real nasty pasty, and one who's not afraid to let off a nuke or two.

But hey, even if you totally ignore the story you'll still have a blast with COD4, simply because it puts you in so many different situations that you rarely have time to get bored or frustrated with the game. One minute you'll be silently sniping your way through Russia and the next you'll be piloting an AC-130 Gunship. One mission I loved was when you have to utilise the night vision goggles to great effect. Seeing your comrades' green scopes all over the place as well as witnessing gunfights in this mode really needs to be seen to be believed. You really will feel like you're there, which is a huge accolade for any game regardless of genre.

I've mentioned that the graphics are fantastic, and they are, but this high level of design also carries over into pretty much every other part of the game. Sound effects are accurate and crisp, and you'll learn to hear the enemy from afar before you can even see them (not to mention soil your pants when you hear the menacing bark of patrol dogs). Level design is highly scripted but as I've said you never really feel manipulated. It's so darn fun and visceral that you can forgive the rather linear nature of each level. I also feel that the sheer variety of levels on offer here really sets this game apart, particularly in its use of vignettes for particularly nasty things that happen to characters (yes, people will die and you will be right there to witness it).

So what about some negative points? Well, the game does use a fair few archaic elements. The most noticeable of these would be the re-spawning enemies. Each level has a number of action set-pieces where you'll be pinned down and have to push forwards in order to get anywhere. In these situations enemies are pretty much endless, so it can be quite frustrating if you're the type of gamer who likes to pick off every last enemy. This design decision forces you to keep pushing ahead, but on the harder difficulty levels this will more often than not result in instant death. The counterpoint to this is that enemy AI is absolutely fantastic; they will flank, retreat and call out your position to their countrymen (in another language of course). Also, when you shoot a soldier in a body part that doesn't equal instant death, they'll often clutch their bellies, limp off or even draw their firearm in a last stand effort to get back at you. This is particularly impressive given that the game streams along with an impressive frame-rate despite all of the action that takes place.

Some players will also be disappointed at the lack of some kind of cover system. You'll spend a lot of time ducking behind cover, so it would have seemed prudent to think about including either a cover system like R6: Vegas or a leaning ability like that seen in Medal of Honor: Airborne. Still, it's hardy game breaking, and as I've said already the game actually encourages you to keep moving even at the risk of death – kind of like real war I guess.

Of course, the most impressive thing about COD4, as a game, is that it's managed to include both an engaging single player experience and a robust (and addictive) multiplayer component. Simply put, the game's multiplayer is good enough that it could have been released as a stand alone game. Although there are no multiplayer achievements to be had, playing against irate Yanks yields its own rewards. The game's XP system is so addictive that you'll soon be wondering where the last six hours went. There are so many different modes to multiplayer – from free-for-all and team deathmatch through to domination, headquarters and sabotage – that most gamers' preferences should be met.

Every kill that you get nets you points, which allows you to level up and gain access to better weapons and perks, such as Last Stand, a grenade launcher, deeper bullet penetration and more health. The awesome part is that you can actually see your XP as you play the game, with "+10” popping up as you kill someone online. You can also level up mid-match, which is enough to give you a huge grin and keep you hooked for another round. The maps themselves are also designed masterfully. You can opt to play the game hard and fast, a la Counterstrike, or you can form a group of like-minded tactical souls and try to defend a particular point against assault. It's this kind of accessibility with optional depth that makes COD4's multiplayer one of the best that we've seen in the genre.