Undead Nightmare takes Red Dead Redemption in the realm of the survival horror game by changing a few gameplay mechanics. Most importantly, ammo is much more limited than in the main game. There are no shops to purchase it, as they all closed because of the zombie outbreak, and only a few of the enemies you kill will be carrying some, the ones with a holster and ammo belt which implies they were a gun-slinger in their previous life. Ammo becomes a form of currency in Undead Nightmare, you are given it when you complete missions and some of the random events which occur as you travel around. This works fairly well, but I never found myself really short of ammo except at the very start, the amounts you are given are more than ample, and if I ever found I was running low on one type I always had enough of another to give me a backup weapon. You’d only really be in trouble if you were a terrible shot and never used the slow motion Dead-Eye mode to get head-shots all the time. Another thing added to add to the survival horror feel is that the first time you encounter a settlement in the game, even some really small ones, it will be under attack from zombies, if you fight them off you will then be able to save your game there. You can also fast travel between the settlements you have saved, the camp site ability which enabled fast travel in the main game isn’t present in Undead Nightmare. After a few days of in-game time has passed after a settlement was saved, it will come under attack again, so you have to go back and rescue it again if you want to save your game there. This could potentially have got quite annoying, if you had to run off to different settlements every few minutes, but after I’d completed the story, and got 100%, I’d only had to go back to the first four settlements I’d saved, out of a total of 22, so it’s not too bad.
Perhaps it was because I went straight into it after finishing the story in the main game, but I thought the story in Undead Nightmare was a bit short. I was also pretty disappointed by the ending, it seemed quite abrupt, when I started the last mission I wasn’t really expecting that to be it. All of the missions are set up like the Stranger missions in the main game, so you can complete a part of one then do part of another, and a few times you need to wait until you can do the next bit. Some of the missions you have to do, in particular one where you need to pick some herbs, were a bit boring. But there were a few that were better, such as one that involves crossing into Mexico on a train. I definitely found the dialogue in Undead Nightmare funnier than the main game, a highlight being a rant by one character which blames the zombie outbreak on pretty much everybody but white Americans. During the game you get the chance to tame each of the Four Horses of the Apocalypse, unlike the regular houses in the game they have infinite stamina, allowing you to get about faster, and they are also pretty much invincible. Each horse has a unique look, War, for example, has flames coming out of it, but unfortunately these effects have the unintended consequence of making the frame rate drop quite low sometimes. In fact riding around in the wooded area of Tall Trees on one of these horses makes the game almost unplayable. Occasional frame rate drops were common in the main game, but they are amplified by the Four Horses because the game has to render quite complex flame or cloud effects all the time you are riding them. It became a bit of an annoyance as I played, and did detract a little from my enjoyment. Though despite these odd technical problems and the occasional dragging of the story, overall I still found it to be quite fun, perhaps more so than the very serious main game, so I think Undead Nightmare is a worthwhile addition to the game.