An addictive shooter that becomes even better when played with friends.
The premise in Left 4 Dead's single-player is a simple one: trek through one of four maps and avoid getting killed by the relentless zombie threat... easier said than done. Each map has five individual "levels," the first four of which end in a safe house in which you can stock up on ammo and heal yourself and teammates, free from the zombie threat lurking outside. The safe houses break up the action nicely; you'll never feel like they're cutting up the map too much -- If anything, you'll welcome them. On the last level, however, you wont get the luxury of a safe house. Instead, you'll have to fend off the zombie horde long enough for your rescue vehicle to arrive, which is how all four maps end.
As with its other games, Valve did an excellent job with the in-game environments: the levels are strikingly modeled as if the zombie apocalypse really did occur. Windows are smashed, buildings are beat up, and houses are devoid of all normal human beings, often left in the state they were before their occupants turned into zombies -- alarms are still going off, computers are left on, etc. Plus, you'll see various bits of graffiti documenting other's experiences trying to stay alive and fend off the overwhelming horde of zombies. This is especially prevalent in safe houses, where you'll see writings on the wall containing words of caution, frantic pleas for help, and even family members looking for each other.
These environments Valve crafted really make you feel like you're a part of this catastrophe -- the same goes for the in-game sound effects. The grunts, screams, and groans convey the savage nature of the zombies, while your ally's banter is both amusing and helpful; they'll warn you of incoming threats, and if they're in good enough health, they might even pop a couple jokes. That said, the character models are top notch. As your allies become hurt, they'll look and sound hurt and scared, growing more frantic the lower their health depletes. The characters really feel like they're your friends, not just another couple AI bots. The music in Left 4 Dead also immerses you in the experience: If a special infected is lurking around, you'll hear spooky music -- the same goes for times when a horde of zombies is approaching. Though the story line is almost nonexistent in Left 4 Dead, you'll still feel completely immersed in the four relatively short single-player and co-op campaigns.
The short single-player (or co-op) campaigns are one of the few downsides in Left 4 Dead: you can blow through all four of them in less than four hours, even on your first try. Luckily, the game randomizes enemy encounters, so no map play-through will theoretically be the same. At a given location on your first play-through, you might have to fight a large number of normal zombies and a "tank" (the name is fitting -- a tank is a brute-like zombie with enough strength to incapacitate you in a few hits, depending on the difficulty you're playing at). However, on your next play-through, you might only fight a few zombies and no tank at that same location. You'll always have to be on your feet, and thus, the four linear campaign levels never really get boring. This system does have its limits, though: if you play the campaigns enough, you'll know the spots where certain events are likely to happen. If they don't happen at that exact location, they're likely to happen a bit after or before where they "normally" are.
Another of Left 4 Dead's downfalls is the friendly AI. The AI does a good job doing basic functions such as helping you up after getting incapacitated, or saving you from a pouncing zombie, but that's about it. For example, if you want to play the game strategically and climb a ladder to hole up while the zombies are attacking, your friendly AI usually won't follow you, and thus will be subjected to all threats below. The AI also won't take advantage of Left 4 Dead's explosives, the pipe bomb and the molotov cocktail. Though, as mentioned, this can all be remedied through four player co-op.
If you do happen to get bored with single-player and co-op, you can try Left 4 Dead's multiplayer. Versus mode, as it's called, supports up to eight players per game -- four players taking the roll of the "survivors," and the other four taking the roll of special infected zombies. You'll take turns being human and zombie, competing for the best score once the campaign is completed. One team will tackle the first level as survivors, the other team trying to prevent them from completing it as the special infected. After the humans succeed or are killed, the former zombies tackle the same level as humans. This continues through all of the five levels within one campaign, after which, the scores are tallied up and a winner is determined.
Multiplayer matches are easy to find, but not quite accessible to everyone. Prepare to work as a team, utilizing the microphone, or you'll likely be booted from the match. Not only that, but you probably wont survive very long. You'll also probably want to know the gist of each level before you venture into multiplayer mode, as the game rarely puts you into a game in which everyone is at your skill level -- it's very likely to be thrust into a match full of veterans your first time playing multiplayer. Despite this inaccessibility, those wanting more than just co-op and single-player will enjoy Left 4 Dead's "versus" multiplayer mode.
Although Left 4 Dead has a couple annoying qualities, it's still a very intricately crafted shooter that will hold your attention long past one play-through of each campaign. Though they're short, the campaigns remain interesting by adding random enemy spawns and occurrences. Jump into one of the four campaign levels or play multiplayer with friends, and the experience becomes even better. With that said, Left 4 Dead is definitely a shooter you won't hesitate to play more than once... or twice... or three times.