Ever since the very first release, the Call of Duty series has been considered a top tier shooting game time after time. Focusing on the very popular World War II era, the COD series always managed to combine cinematic story with action packed gameplay that oozed quality and attention to detail, taking home many GOTY awards over the years. Unfortunately for us PC junkies, COD 3 never made it to the world's best gaming platform and quite honestly it appeared that Activision were never going to bring the series back. Fortunes change however, and with the release of Call of Duty 4: Modern Warfare comes the return of COD to the PC platform, and what a return it is.

COD 4: Modern Warfare, as the full title would suggest, is no longer based on the WWII era of warfare that defined the COD series. This must have been a tricky decision to make by Activision and developers Infinity Ward as while the WWII shooting genre was starting to reach its peak with COD 2 let alone COD 3, the modern warfare shooting genre is not exactly needy itself, already featuring considerable quality mainly from the Ghost Recon and Rainbow Six series. With this in mind, COD 4 really needed to be something special and something very impressive to take such titles on, and not only is this achieved, but COD 4 could quite easily be the best modern era shooter you have ever played, if not the best shooter in general.

With today's world of global terrorism and nuclear warheads spread across multiple powers, it isn't hard to imagine the type of storyline that the singleplayer campaign mode in COD 4 portrays. With some special exceptions aside, the vast majority of the campaign mode puts you the gamer into the shoes of either a British SAS soldier by the name of 'Soap', or a US Marine by the name of Sgt. Paul Jackson as you ultimately try to prevent notable figures in extremist Arabic and Russian factions from securing and using nuclear arms on the Western nations. Most missions in the game are either located in the urban Middle East or country side Eastern Europe regions although a few exceptions exist here and there.

The first impression you'll get from the gameplay in COD 4 is just how well rounded and solid the engine is. The feel as you move about is very authentic, from the kick back on the game's many included real world guns to the earth shattering physics of explosions. Even the very simple stuff like being able to hurdle objects and obstacles to effectively using objects as cover shows not only how much attention was directed at making the small but important things work right but it also shows the emphasis put on the engine to be versatile enough so it wouldn't restrict any of the action. There is no better proof for this than the game's variation, and by that I don't just mean changes in scenery and changing in weapon types - I mean variation in the core gameplay itself.

A lot of shooters these days give you a gun, tell you your objectives and throw the same style of gameplay at you over and over again until the ending credits, but COD 4 isn't like this. The COD series has always tried to spice up the action by providing variation in what you do and how you do it, but COD 4 really takes the cake in this regard. As mentioned, the game revolves around the usage of both SAS and USMC soldiers and the gameplay differences between the two are very distinct. As 'Soap' of the SAS you will be taking on more discreet stealth style missions that, while being action packed, aren't quite as 'wham, bam thank you uncle sam' as the USMC missions and the contrast between the two as both storylines intertwine makes for gameplay that never feels dull. The highlight of the game's variation would have to come with a mission titled 'Death from Above', which tasks you with the role of a gunner on a AC-130 gun ship (modern version of 'Puff the Magic Dragon') firing down on hostile forces from well above in the night sky - this sort of wide spectrum of gameplay is a trademark of the COD series and COD 4 is no exception.

Perhaps even more integral than the variation to the fantastic singleplayer experience is the challenge the game will provide mainly thanks to the game's tough but fair AI. With four difficulty settings on offer, the game provides everything from an extremely easy to an extremely tough experience that will suit just about every level of FPS gamer out there. Regardless of the difficulty setting though, it is clear that a lot of energy was directed towards making baddies in this game smart to play against and not just powerful in sheer numbers (although at times the game will not hesitate to combine both smarts and large numbers). They will use cover effectively, and you'll most certainly be killed a few times by intelligent grenade placements that take you off guard - hell, the baddies in COD 4 will even pick up your own grenades and throw them back at you at times. This intelligence also translates into actual effective AI friendlies in the game, which are by your side in most missions, although it is clear the game doesn't make them too good as to take significant killing opportunities away from yourself. A very nice balance is achieved that leaves you with plenty to do, but at the same time you never really feel the game revolves around your character which so many shooters fail to pull off.