In fact, the suddenness with which you can find yourself going from a massive battle area into a tiny one (basically as you run through a house door) is quite dizzying, and ensures you can never rest easy around the same sort of attack or defend routine.

In other words, just like in a real war you have to stay on your toes at all times, or you're dead.

As we'll see in the following sections of this review, no technical stone is left unturned in making the experience of playing COD4 as intense and unrelenting as possible. Plus many of the missions feature near-perfect map designs, and the variety in terms of goals and gameplay techniques is outstanding.

Really my only concern in gameplay terms is that you should pick the level you play the game at with care. I played on the hardest, Veteran level (gamerscore whore that I am), and have to say that while this added greatly to the longevity of the game, it also meant that I had to be so absolutely obsessed with watching my ass that I didn't get chance to simply enjoy the COD4 view as much as I'd liked to have done.

That said, even if you only play through on 'normal' difficulty initially, I strongly recommend that you return to it on Veteran later just to experience the stunning intensity of playing the game when you know that pretty much getting shot even once will cause a quick and unpleasant death. Just charging at those pesky Russkies singing Three Lions doesn't cut it on Veteran level, I can tell you.

The achievements for COD4 on the 360 are quite strange, in that they don't feature a single online one - presumably because Infinity Ward doesn't want to penalise Xbox 360 owners who don't have broadband and so can't enjoy online play. But personally I wouldn't have minded at least a couple of basic 'level up' style online achievements to spur you on.

Also, the main game achievements are for the most part slightly dull, with the majority simply rewarding you for finishing levels. Only a small handful go down the route of trying to get you to do things in the game you otherwise wouldn't necessarily bother with, such as shooting down a chopper with an RPG. In fact, the only 'extra value' thing the achievements really encourage is playing the game through on veteran, for which you can rack up points galore.

One final addendum here: such is my dedication to the HD Wars cause that I finally finished COD4 on Veteran. Which, I don't mind telling you, made me feel pretty damn pleased with myself once my nerves had recovered.

But then the damn game has the temerity to shoot my momentarily swollen ego down in flames with a fiendishly hard Epilogue level that I've now failed to even get close to finishing on Veteran on 186 separate occasions. And yes, I really am counting. Tragic. If I ever DO complete this total sod of a level, don't worry: I'll update this review. Not because adding such information will be of any use to you, of course, but just because I want to crow about it.

The graphical prowess on show is evident in three main ways. First, the level of detail in environments is excellent, putting the previous two 'next gen' COD games to soft and fuzzy shame. Second, the scale of the environments is outstanding. Sure, the previous games have had their epic moments, but here almost every level has the draw distance (without a trace of pop up) to make you feel as if you really are just a tiny cog in a huge war machine - a feat that makes you feel both humble and empowered all at the same time, oddly.

The last great thing about the graphics is how silky smooth they are. Environments glide by without a stutter or glitch no matter how much is going on at once, and regardless of what speed you're moving. If achieving such outstanding smoothness as this is why Infinity Ward dropped the resolution a touch, then it's a trade I'm more than happy to make.

The speech is well mixed too, so that you can always make out what characters are saying no matter how noisy the action is around you, and the quality of the voice acting is surprisingly good.

To round things off, the game also features a very atmospheric score that knows just when to step up a gear to make your heart pound even faster.

First of all, Xbox Live play seems terrifically stable. I've played many hundreds of games on there at the time of writing (sad, I know), and suffered only minor lag on a couple of occasions. For 99 per cent of the time the game engine runs silky smooth without a twitch or a glitch in sight. Which sadly means that if I do crap, I can only blame myself, not a lagging network. Darn.

The multiplayer maps are, for the most part, superbly designed and quite varied, having just the right blend of wide open spaces, sneaky sniping holes, and tense, tight interiors.

Also commendable is the excellent online levelling up system Infinity Ward has implemented. With no online gamescore achievement points to keep you keen, the game cunningly gives you instead really good kit and ability 'upgrades' for securing enough points in ranked games to get your military rank rising. Upgrade options include such beauties as increased bullet power, the ability to listen in on opposition team dialogue, and a Last Stand facility that lets you whip your pistol out and fire a last shot or two before you die. Killing someone with one of these Last Stand shots is quite ridiculously satisfying, by the way.

You also get an impressive five memory slots where you can store customised combinations of the abilities and equipment you've earned, so that you can, say, build a sniper specialist for certain maps, and a heavy arms specialist for others.

With that next level up and its lovely new kit bonus always tantalisingly close, the whole inspired online system adds up to a classic recipe for good old-fashioned addiction.

Obviously the system of rewarding your advancement with enhanced weapons and abilities has the potential to horribly unbalance the game environment, making it too easy for high-level players and too difficult for new players. But actually, even though my first few games were straight free-for-all deathmatches against people ranked many levels higher than me, I never felt like I wasn't competing. Yet somehow I also felt the benefit of all the extra features as they became available to me. In other words, the balance seems pretty much perfect.

As if all this wasn't enough, COD4 also boasts a truly prodigious set of online game options. There are no less than 14 game types: Team Deathmatch, Free for All, Domination (where 3 flags in a level must be captured to earn points), Ground War (big team games featuring up to 18 players!), Sabotage (6-12 players, where teams try to use a bomb to destroy the enemy's objective), Headquarters (6-12 players battle to capture and control neutral bases), Search and Destroy (6-12 player matches with no respawns where you have to defend or destroy an objective), Team Objective (6-12 player team-based takes on Domination, Headquarters, Sabotage, and Search & Destroy), Team Tactical (4-6 player games based on team deathmatch, Domination, Headquarters, Sabotage and Search and Destroy), Team Hardcore (Limited HUD, extra bullet damage, friendly fire on), Old School (no classes, weapons are pickups, health increased and jumps are higher), Cage Match (Old School 1v1), and Oldcore (Team Deathmatch with 6-12 players, old school pickups and jumping, hardcore limited HUD and extra bullet damage). Phew.

Initially you can only access the Team Deathmatch and Free for all options, with the rest only opening up as you achieve certain military ranks from your point-scoring online. This provides yet another reason to keep on playing. Though really the sheer joy of playing the game online is all the reason I needed.

Other great elements of the online game include the keeping of comprehensive stats on stuff like shot accuracy and kill ratios; and the ability to choose to either set up your own private 'just for friends' matches or else jump straight into a 'global' match where you can earn ranking points.

I was chuffed to note, too, that Infinity Ward allows you to invite friends into 'ranked' games. This obviously opens the game's 'levelling up' system to abuse by people sad enough to exploit it, but for most normal, socially adept people who actually have lives, it's a really friendly feature that adds greatly to the simple fun of the COD4 experience.

Great though COD4 online is, though, I've still managed to find three gripes with it that cost it a couple of online marks.

First, you can only have one person signing in per Xbox. There's no split-screen online support. Second, there are no co-op campaign modes a la Halo 3 or Gears of War. And finally the ranking system doesn’t really match you with gamers of a similar skill, a la Halo 3.

But these niggles only detract a little from what for my money is the finest online gaming experience consoles currently have to offer.

And don't forget that while the single-player may lack longevity, the outstandingly comprehensive and hugely enjoyable online multiplayer experience can keep you going for, well, pretty much ever.