"If you enjoyed Oblivion, then Knights of the Nine is for you, but it's not going to change your mind if you didn't."
Everyone that I'm aware of who played Oblivion had either a love or hate relationship with it. For me, it was love. I spent hundreds of hours combing over the vast landscapes of Tamriel, delving into hidden dungeons, completing quests, and unloading millions of arrows into my enemies. That's not to say it didn't have problems, however. Dungeon environments were frequently recycled, there were plenty of bugs, third-person combat was wonky at the best of times, magic management was awkward, and much of the environment lacked variety or any specific points of interest. If you enjoyed Oblivion, then Knights of the Nine is for you, but it's not going to change your mind if you didn't.
The Knights quest begins when the chapel in the seaside city of Anvil is attacked. After sending your character to investigate the wreckage, which includes runes written in blood, you'll encounter a prophet who fills you in on the situation. Apparently, strange enemies are laying siege to the chapel led by an ancient sorcerer-king, and if someone doesn't act, the world will be at risk! It's up to you to save Tamriel from this menace by restoring the Knights of the Nine to their former glory and locating all of the Crusader Relics! It's typical fantasy cliché and it doesn't develop much of an arc, but there's no doubt that it is the perfect quest if you play a knight or paladin style character. The whole game is reminiscent of classic knight myths of history like the story of the quest for the Holy Grail. Many characters join your cause, and some can help you in fights or provide you with information. Unfortunately, they're all about as interesting as planks of wood, and it's unlikely you'd care much if they were left in the depths of a dungeon forever. In other words, they're on par with the rest of the characters of the Oblivion world. Actually, due to a bug, I accidentally did leave one behind in a dungeon. Never saw the poor guy again.
Luckily, the gameplay is far superior to the story; it's definitely the highlight of this DLC. It starts off weakly, but improves the further you play. The initial quest sees your character trekking across the countryside in search of a shrine for each god. You get a basic map to help you find them, but there's no fast travelling there, so it can take quite some time to locate them. If you do not yet own a horse, this is the perfect quest to buy one for. Most of the other tasks of the game involve exploring ruins for ancient weapons and armour that make up the set you can see in the screenshots to the right. The dungeons use the same recycled rooms as other Oblivion caves and ruins, but there are a few puzzles thrown in for variety. One memorable challenge has you collect a couple of scattered clues to figure out the order to press a set of switches. The included puzzles are quite simple, especially compared to other games, but they're a nice change for The Elder Scrolls and aid in creating unique dungeons.
As you may expect, collecting each relic involves a test. Some of these are simply clearing a dungeon, but most are a little more unique. In the quest to get the Crusader Boots, for example, you'll have to respect the local wildlife to appease a Daedra who knows the location where the armour rests. Another has you "test your faith" and cross a bottomless abyss. If you get to this point, don't do what I did and think along the lines of Indiana Jones and the Last Crusade. Walking blindly across the gap will just see you fall to your death. My favourite, though, was the side-story involved with recovering the gauntlets. After they'd been used to kill a man inside a chapel many years ago they'd fallen to the ground and a magic had made them impossible to move. Now they sat in a cob-webbed corner of the chapel as a sort of weird tourist attraction. Trust me, picking them up will be no easy task!
The armour set will either be light or heavy depending on which of these skills are highest for your character. This means even an unarmoured mage or a lightly armoured assassin can still wear and use the Knights of the Nine equipment fairly effectively, which is a nice little bonus. Once it is all assembled you can head to the final dungeon and take on the boss. This one proves to be a little more interesting and includes some fun cut-scenes, a two-phase final battle, and all the knights you've recruited along the way get to come and fight with you. It's not going to rock your world, but it's a fitting end to the saga.
As you may expect, Knights of the Nine simply adds content. It doesn't modify graphics, add very much music, or change core gameplay mechanics. If Oblivion didn't suit your fancy in the past, then Knights of the Nine is highly unlikely to change that. However, if you did enjoy the game and you're looking for some extra content, then this DLC might be the right choice. It's definitely best suited for knight-style characters, but there's fun to be had for all. At only around 5-10 hours in length, you may find it a little short, so if you can nab it at a discount, then go for it. Paying full price is a little bit tougher to justify.