Left 4 Dead: Compelling Co-op
November 12, 2009

On the eve of the release of the sequel to one of my favorite FPS’s of all time, Left 4 Dead, I would like to explore what I believe to be its greatest design strength: its implementation of the classic co-operative mode (one would hope this is its greatest strength, as the whole game is really just one massive co-op romp).

For this analysis, we’ll assume that the players are playing on a difficulty commensurate with their ability (one very good player can more or less solo a campaign on easy mode). Under this assumption, it’s safe to say this game is very hard. This can be a frequently overlooked design choice in a game, but its difficulty is very central to how it appeals to its audience. Make the game too easy, and its boring; make it too hard and you risk frustrating your players. Most games get around the “too easy” problem by adding additional difficulty levels, but the “too hard” problem is a bit more delicate. Hardcore players will strive to beat the game on the hardest difficulty, and accordingly it should be just difficult enough to provide them with an extreme challenge while still being possible to defeat.

Left 4 Dead does an exceptional job of balancing these difficulty levels (often with the help of the AI Director, who makes subtle tweaks to the difficulty based on the players’ performance). The most important effect of this extreme difficulty is it requires the players to work together seamlessly. Even one weak link in the group will bring down the entire party. This is of course a blessing and a curse. For just as it is extraordinarily fulfilling to work together like a well oiled machine, it’s equally irritating to fail time after time due to a less experienced teammate.

One of the annoying problems with many co-op games is that players tend to compete viciously for items and weapons. This rivalry often turns into a meta-game within itself to see who can collect the best stuff, and therefore make the most progress toward the objective (kill the most bad guys, etc.). This does not foster a team mentality and usually detracts from a co-op experience. Fortunately, weapons in L4D are infinite. If everyone wants the shotgun, they can all pick up an instance of the shotgun. Granted, this detracts from the realism, but the benefit in gameplay more than makes up for that. The items that players can get a bit greedy with are the finite health items (med packs or pills) but the player greed here is offset by their will to beat the level. If myself and my terribly wounded partner are the last two remaining in the party, and I’ve been hoarding the last med pack, I’m very willing to give it up because I realize that without him I have no chance of survival. Which brings me to my next point: the dangers of going it alone.

Anyone familiar with the game has come to this unfortunate revelation early in their career: if you’re alone you’re as good as dead. The special zombies have been carefully tailored to wreak the most havoc on lone individuals. The hunter will pin your helpless body down until your dead. The smoker will do the same thing to a loner, but has the added advantage of being able to easily pick off stragglers as well. The boomer, while a bit more complex in that it doesnt explicitly incapacitate the players, makes it extremely difficult for a loner to defend themselves. These foes are designed especially to keep the party tight and working together (if by no other way than natural selection). This ensures that the party doesn’t develop that oh too common hurried leader that runs ahead and kills everything before anyone else gets to have any fun. That guy’s dead outta the starting gate.

One fun twist in the game theory behind surviving the level is that only one person needs to survive for the party to advance to the next level. There comes a point in the game, when the safe room is in sight, when suddenly chaos breaks out and it’s every man for himself. Inevitably, some players will be left for dead (I couldn’t resist). This is often the most tense and usually hilarious segment of the level, when the alliances all suddenly crumble in favor of individual survival. While those left for dead can sometimes feel abandoned and bitter over this, the game leaves them some comfort in knowing that only one of them needs to make it and that they gave their life for the good of the team.

All in all, L4D is truly a model of a well thought out cooperative game. Sure its got its quirks, and player skill can often influence how fun the game is, but its not too hard to get good at (as far as FPS’s go) and has incredible replay value. Way to go Valve! And I anxiously await L4D2 (or, as I was hoping it would be called, L5D).