The first piece of downloadable content (or DLC) for Valve’s highly lauded zombie shoot-’em-up Left 4 Dead was released on Tuesday, bringing with it a host of additions, the most notable of which being the addition of two new Versus campaigns and an all-new game mode known as Survival. Did I mention yet that this DLC is entirely free?

The two new Versus campaigns might sound exciting, but is in fact a minor addition, as these campaigns are simply Versus versions of existing Campaign mode campaigns. This does however add some much-needed replay value to the fantastic Versus mode. For those unfamiliar with the game, Versus mode pits four Survivor players against four Infected. The Infected are given the advantage of being able to see the position of the Survivors at all time, and when killed, can choose a point in the level to spawn at. To stop this becoming unbalanced, the Infected have a low amount of health and obviously lack guns or medkits.

The newly introduced Survival mode is the best new content in this piece of DLC. Players choose a level, which can be any level from the four Campaign campaigns or an all-new one-level campaign called “Last Stand”, set on an abandoned lighthouse. Players must survive as long as they can in an almost never-ending flow of Infected. A timer measures how long you’ve survived for, and also records your best time so far.

Survival mode introduces a few new Achievements, virtual awards you receive for performing various feats in the game. Left 4 Dead already featured over 50 Achievements, and this DLC introduces seven more. These range from easy-to-attain ones such as “Bronze Mettle”, awarded for surviving 4 minutes, to “Legendary Survivor”, requiring you to acquire a Gold medal on every official Survival level.

But don’t think that you’re restricted to just the official levels. The upcoming release of the official Left 4 Dead SDK will allow skilled mappers to create their own campaigns. Bored with the official levels? It’s likely that somebody is already planning on creating a custom level featuring an all-new scenario such as a shopping centre, the interior of a plane, or some other obscure location. Still not creative enough for you? Imagine you’re on a boat - maybe even the Titanic - and there are zombies all around you.

Seeing as the new Survival mode and Versus campaigns add a great deal of content and new replay value to Left 4 Dead, all for the low, low price of absolutely nothing, I award Left 4 Dead’s first piece of downloadable content (which hopefully heralds more in the future) a final score of 96%.