If your a fan of intense shooters you don't want to miss Call of Duty 4: Modern Warfare. Infinity Ward has really raised the bar for "realistic" shooters.
The single-player has you in the boots of U.S. Marine Force Recon and British S.A.S. Your tasked with dealing with a nuclear threat posed by a middle eastern extremist coup, and an ex-soviet group hell bent on taking Russia back into communism.
The locales are varied enough, and fit the story well. You will battle in mid-east markets, rural Russia, a cargo ship, and the "dead zone" of Chernobyl to name a few.
The story is suprisingly good, considering the track record of similar games. I won't ruin anything with spoilers, the experience is rather sobering, but thoroughly worthwhile nonetheless.
The graphics are some of the best seen so far in this era of gaming. Character models and animations both look fantastic. Lighting and particle effects add to the realism. Bloom lighting and depth of field simulate the human eye to a believable level. The game looks especially stunning in the single-player campaign.
If you have 5.1 surround sound, then COD4 will certainly "wow" you. The weapons all have unique reports, and are recognizable after playing for while. Hearing all hell breaking loose around you is sure to put hair on your chest, and a lump in your throat.
This brings us to the online multi-player. COD4 has a full multi-player suite of game modes. Ranging from 1v1 Cage Match to 9v9 Ground War. You start as a lowly Recruit and work your way up the ranks unlocking a host of goodies on the way. This is where COD4's perk system comes into play. Various perks allow you to "fine tune" your soldier for maximum lethality for your style of play. When you reach the level cap, you are faced with a tough choice. Prestige mode is the next progression of the multi-player after you reach the level cap. When you enter Prestige mode, you level is returned to 1, and everything you had unlocked is relocked and must be gotten again. The plus side of doing this is that instead of a rank insignia, you will have an actual armed forces medal beside your name.
In closing, COD4 is arguably one of the best shooters of 2007. If you are even remotely interested in the fps genre, do yourself a favor and give COD4 some playtime.