The 4th installment of Call of Duty, by developer Infinity Ward is perhaps the best First Person Shooter of 2007. Rivaling that of Halo 3, CoD4 brings something new and different to the table that past CoD games have not had.

While the single player is lacking in a longer story mode, it is very much action filled and intense. As you travel across the world playing as a member of the British SAS or the United States Marine Corps, you are taken on a journey that is all too familiar to modern conflicts. Without giving too much away, allied forces have taken to war to defend the world from a Middle Eastern military leader.

The single player plays out in many different locales, from the dry and dusty streets of Saudi Arabia to the desolate ghost town of Pripyat, Ukraine. The levels of difficulty seem to be on par with previous Call of Duty games, with four different difficulty bars. Despite the shorter story, not much is wrong with CoD4's single player. While the addition of online co-op would have been nice, it is really not needed as the game sweeps you along.

The real fun of Call of Duty 4 though is the multi-player. Included on the disk is 16 multi-player maps of ranging size and scenery. Each map is also taken from a level found within the game itself, altered, and re-created for online play. New to the table though, is the multi-player perks, and weapons challenges.

Players start off their online character as a basic soldier, with not much to choose from in terms of weaponry. As players progress in the ranks, and get kills with specific weapons, they can earn special attachments, such as a Red Dot Sight (to improve accuracy) or a Silencer (to give stealth). There are also several camouflage patterns that players can use to modify the look of their weapons.

The perk system allows players to pick three different bonuses to aid themselves in battle. Limited to just three unique perk classes, players must choose their perks wisely. As players level up by winning games, getting kills, and completing challenges, they unlock new weapons, and perks.

Once a player has reached level 55 on the first playthough, they have the ability to enter "Prestige Mode." What this does is it takes players from level 55, and drops them to level 1. Players start from scratch, but now have a unique and cool symbol next to their name that denotes which level of prestige the player is in (there are 10 levels of prestige).

As a whole, Call of Duty 4 is a strong game both online and offline. Where the game excels though is in the online multi-player. The challenges, perks, and unlockables offer something new and different for players. It gives players a reason to play longer and with specific weapons to "level them up." Infinity Ward made the right decision in moving away from the WWII era, and bringing Call of Duty in to the realm of Modern Combat.