With a short-but-sweet campaign, and incredible multiplayer, COD4 is nothing short of awesome!
When you do beat the campaign, you unlock the arcade mode, which lets you play through any mission and get a high score by killing enemies and other actions. But the real treat upon completing single-player is multi-player. Up to twelve people can duke it out online on nearly 16 maps. Arguably, multi-player best feature is "create-a-class." This lets you pick your weapons as well as perks, which are traits that give your character special abilities on the battlefield, such as high conditioning (longer sprints), RPG x2 (a rocket launcher with two rockets), last stand (pull out your pistol right before you die to get a last-minute kill), and eavesdrop (listen to your enemy's chatter over your headset.) You can only carry three of these, so you must choose wisely. Fortunately, none of them feel overpowered. As you continue playing, you get XP (experience points) and the more XP you get, the more you can level up which unlocks more weapons and perks. With the combination of a short, but powerful single-player campaign and multi-player that never get old. Call of Duty 4 is nothing less than perfection, and is a no-brainer purchase!