The popularity of Red Dead Redemption caught Rockstar unawares earlier this year, although with the benefit of hindsight it should be obvious why. Gunslinging cowboys? Check. Gritty narrative? Check. Sandbox world? You got it. Job done, drive the front-end loader full of money to the bank.

Except it's not quite as simple as that. Redemption's singleplayer mode always felt stunted, the West Elizabeth missions in particular smacked of rushed delivery and suit-wearing executives nervously pacing a groove into the development studio's shag-pile carpet. Singleplayer DLC was always on the table, but not many suspected it would take the form of a B-grade horror homage, fewer even than that must have anticipated John would return to slaughter the long-dead inhabitants of the dusty frontier.

The premise is as silly and fantastic as you'd expect - the undead have risen, they're angry, and have a severe case of wanting to kill you. Rockstar have redesigned the entire game UI around the new mode, in a similar fashion to the Gay Tony and Lost & Damned add-ons for GTA IV, so you'll be treated to full immersion the minute the game starts. Which is just as well, as you can't be reminded enough just how perilous the situation is.

Unlike the dour, shuffling, idiotic zombies in films such as Shaun of the Dead, these undead are fast. You're also extremely limited in the amount of ammunition lying around at the beginning of the game, and you can't expect to kill zombies with a blast-from-the-hip mentality either - you'll need to specifically go after headshots, which means the deadeye mechanic gets a workout. More often than not, it's best to get in close and use one of the games finishing moves to dispatch your foe; perhaps Rockstar felt they were underutilised in the original Red Dead release, but whatever the reason, get used to using them.

The new missions are really just rehashed versions of existing challenges - instead of clearing out a gang hideout, you'll clear out a graveyard. You'll still play a FedEx employee on occasion, and random encounters typically involve saving strangers from becoming human hamburgers. Throughout the five to six hours of content, you'll follow the plot and uncover various theories as to the cause of the outbreak, introduced by new cinematics infused with Rockstar's brilliant dark humour.

Economically speaking, money is out. Mission success carries with it a reward of ammunition, or new weapons. The honour system has also been banished to the cutting-room floor - it's really up to you to survive as best you can, and if that involves killing other survivors then you can do so without punishment. The campfire save mechanic is also out (would you want to camp in the open with hundreds of zombies around?) so assisting townsfolk to repel incoming invasions will provide you with a safe house where you can save your game instead. You'll want to do this frequently, as death results in a respawn either at your last saved location or outside the walls of the nearest town, which can frequently result in another fairly rapid death.

The safe houses also serve as portals to fast-travel between towns you've previously occupied, although to encourage players to explore the new world, Rockstar have introduced four undead mounts which have infinite stamina and move at a blistering pace. War, Pestilence, Death and Famine must be captured and tamed (you'll be notified when one is in the area) and each one conveys some kind of advantage to the player; War ignites nearby zombies. Famine attracts a plague of insects. Death causes heads to explode and Pestilence is virtually impossible to kill.

Really though, despite the increased movement speed they're predominantly used as eye candy, as the real fun is in destroying zombies with your assorted weaponry.

Accuracy is the name of the game here - ranged shots must target the head, so to that extent your sidearm and various rifles are sufficient, provided you have enough deadeye. It's not long into the game however that you're provided with a blunderbuss, and it's here that things start getting messy. The 'buss is powered by undead body parts, and is capable of vaporising mobs with a worrying level of efficiency, so it's best not to leave home without it. There are other interesting additions to assist you as well - holy water and zombie bait can be worked in to provide a comprehensive zombie-slaying package.

When you're done with the singleplayer campaign, you can try out two new multiplayer additions. Undead Overrun is much like the Nazi Zombie mode in Call of Duty: World at War, whereby you face down incoming hordes of zombies until you're defeated. Land Grab is, as the name suggests, an attempt to secure seven locations on the map.

They're interesting additions to the DLC, but with so much on offer in the singleplayer mode Rockstar could have omitted these and you'd still have excellent value for money at 800MS points, or $18.90 from PSN.

If you're thinking we won't stoop to describing the purchase of this zombie DLC as a "no brainer", you're mistaken. Rockstar have created one of the most imaginative and cleverly designed DLC packs this year. Anyone with an existing copy of Red Dead Redemption and the means to manage the 1.1GB download should definitely partake.