Template:All Game Nav Oblivion does actually have a main quest, but if you're anything like me you'll ignore it for a few weeks while getting that new sword or reputation with your guild. The main quest is always there to work on, but it's not required at all.
Getting Started and Getting the Amulet
The game basically starts with you in jail. The emperor and his guards have to go through a passageway that leads right through your cell allowing you to escape. This level is mostly a tutorial so I'll let you figure it out. Once you reunite with the king you have to fight off a few assasins. The king will then go into a dead end and the gaurds will tell you to stay with him. Talk to the king and you'll start a cut scene where he tells you to find his frienc Jauffre and show him the Amulet of Kings. After saying that he is promptly killed by an assasin.
Now that you've got the Amulet and you got out of the sewers you're supposed to go to Weynor Pirory and show it to Jauffre. You could just as easily do nothing at all though and screw around in the Imperial City.
Deliver the Amulet
So you got tired of hanging around doing nothing already? Oh well if you want to do the main quest thats fine. So now we're headed for Weynon Priory. There should be a few monks there and Jauffre in the library. Talk to him and he'll take the Amulet of Kings from you for safekeeping (guess how that ends up) and tells you there is a long lost heir to the throne in Kvatch. He sends you there to get him and bring him back so that he's safe from assasins.
Find the Heir
When Jauffre sends you to find Martin in Kvatch it sounds like a simple errand. When looking at the map though you'll notice the nearest fast travel point is a bit south of Kvatch. How odd. On arriving at this point you'll be approached by a panicking elf who explains to you that gates to Oblivion (basically hell) opened up last night and draene (demons) burned the city to the ground. Ask around and you'll find out a few soldiers are trying to keep the demons back. Get up there to lend them your sword.
Talking to the captain he'll tell you that Martin is a priest and hurried people into the chapel to try and wait it out. He also tells you no one can get in unless the gate to Oblivion closes. When you agree to help fight tou and the soldiers will rush a few weak scamps outside the portal. Then the guard captain tells you that he sent some men into the gate and the never came out so naturally you have to go in and fetch him.
Into Oblivion
Inside Oblivion it's the generic hell with fire and brimstone. You'll immediately see one soldier running around fighting scamps. Help the guy out and he'll talk to you. Now you can choose whether for him to stay and help you or go outside and help the captain. I personally suggest you send him out because the "allies" in Oblivion tend to be idiots who charge in front of you and then get angry when you slash them. If you're really lonely though he does help.
The good news is that this place is fairly linear and easy to navigate. The bad news is that this is the first time in Oblivion (assuming you went straight to the main quest) that the enemies pose a threat. These are armored demons not goblins in the sewers. So follow the path and make your way to the tower. Now the odd thing about this tower is it seems to be completely parallel. If you go left it will be a curving pathway into a room if you go to the right it's a mirror image of the pathway and goes to the same room. It is impossible to get lost in this place as long as you keep moving upwards and killing demons.
Eventually you'll reach a floor with a few doors one of which is locked. Go into the other and you'll find yourself on a thin bridge going to another tower (nice architecture for demons) head across to the next room. You'll hear cries for help and climb up to see an old guy (presumably one of the guards sent in) in his underwear locked in a cage. The demon guarding him promptly threatens you and attacks you. You can talk to the guy in the cage or you can do the reasonable thing and kill the demon. The guard then tells you that the sigil keep is home to the sigil stone an artifact that is the heart of this plane of oblivion. Grab the demon's key and head back to that door you couldn't open.
From here on out you'll run into the freaky spell caster guys. Now it's enough trouble with one scamp running around but they are capable of summoning more so don't hesitate to kill the guys in black robes as soon as you see them the scamps he summoned will disappear and continue on your fairly straight path. When you reach the top you'll see a giant flaming stone suspended by chains. Reach over and activate it and the whole plane of Oblivion will explode. You'll be thrust out and watch as the gate closes.
Tell the captain you're ready and you can all rush into Kvatch and kill a few scamps and these weird dinosaur creatures. Then head into the Chapel and talk to Martin. He'll agree to come with you and says we should hurry back to Weynon Priory.
Back to Weynon Priory
With Martin in tow fast travel back to Weynon Priory. On arrival at the Priory the farmhand will run up to you and warn you that assassins are here and then promptly get stabbed in the back. You'll then have to fight several assassins and rescue Jauffre. He'll tell you he hid it behind a cupboard and you'll rush off to find it. As expected the Amulet is gone and Jauffre is dismayed.
He'll tell you that you can have Prior Mabel's Horse (sweet free horse!) and that we should take Martin to Cloud Ruler Temple. Fast travel there and walk up. There will be a short speech by Martin and Jauffre to the Blades and then you'll be thanked by everyone and join the Blades. Now that you've joined you have access to the whole temple. I suggest that you get a full set of Blades armor if you like heavy because it's one of the better armor sets in the game. Talk to Jauffre to make a plan for getting the Amulet back
Reunion with Baurus
Jauffre will tell you that you can meet with Baurus in Luther Broad's Boarding House in the Imperial City. When you enter the place and talk to him he'll tell you to sit down and don't talk too loud. Sit down and he'll explain that the guy in the corner is watching him and that he's going to walk into the basement. He'll stand up and walk downstairs and the man in the corner will follow. Follow the two of them and you'll see that the man is an assassin who attacks Baurus. Help hims out and kill the attacker. Baurus will tell you that he's happy to see you and that he's been collecting information. He informs you that the Emperor was killed by assassins from the Mythic Dawn, a daedric cult that worships Mehrunes Dagon. Looting the body you'll find a strange book called Mankar Camoran's Commentaries on the Mysterium Xarxes, Book 1 (From now on just Commentaries 1.)
Search for the Commentaries
He tells you to take Commentary 1 to Tar-Meena, a mage at the Arcane University. If you're of high standing the Mages Guild she'll move around the University, if not she'll just wait for you in the lobby. Bring her the book and she'll give you some basic information about the Mythic Dawn. According to her the Commentaries come in 4 books and collecting the four books is a rite of passage to find the Mythic Dawn headquarters and join. She'll give you the second book and tell you that she'll work on decoding it. She'll also point you to the First Edition book store as a place to find Commentary 4.
When you arrive at the the First Edition the owner will tell you that he has the book on reserve for a very eager customer and can't sell it to you. Take a seat in the corner and wait for a Wood Elf to arrive and buy the book. Let him buy it then have a conversation with him. When you tell him that the Mythic Dawn killed the Emperor he'll be horrified and immediately give you the book. He'll also explain that Commentary 4 can only be received by a current member. He gives you a note that he received that outlines where to meet a Mythic Dawn member. It is at a table in the sewers so head to Baurus to get a nice tour guide.
Follow Baurus through the sewers and fight off the rats, mudcrabs, and goblins until you reach the room where Baurus stops and turns to you. Now there are several options you can take to approach this next room.
[*]You can kill Baurus and keep your cover when dealing with the Mythic Dawn. This would result in the cultist actually giving you the book. [*]You can tell Baurus to take the meeting. This gives you an oppurtunity to test your stealth. It may be possible to stand by and watch the whole meeting if you find a perfect spot (not on the walkway above.) [*]You can take the meeting and let Baurus watch your back. Two cultists will find Baurus after a few seconds and you'll be thrust into a battle with the three cultists. You'll have to kill them all and loot the book.
No matter which way you choose you have the book and Baurus may or may not be dead. He'll let you navigate your way out of the sewers. Give Tar-meena the last 2 books and give her a day. She'll tell you to go to the Emperor's Way in Imperial City at noon, where something will happen. Head over there and you'll see a glowing map on one of the crypts that points you to a Mythic Dawn hideout.
Infiltrating the Dagon Shrine
There are two ways to approach this quest, but they ultimately lead to the same conclusion.
Stealth Method
Enter the Dagon Shrine and talk to the first guy. He will unlock the door and you will be met by Harrow. Harrow will ask for all your items if you want to blend in give it to him, he'll also mention that you might get initiated into the guild by Mankar Camoran. Later when you kill him you will get all your stuff back so don't panic too much. Follow Harrow through the caverns and into the main chamber. Mankar Camoran will be preaching to a large group of cultists. He'll then turn around and walk into a portal, leaving the Xarxes behind. Your new objective is to get the book and get out. Camoran's assistant will ask you to take a silver dagger and kill an unconscious hostage. Taking the silver dagger will at least give you a weapon. If you kill the hostage you will be welcomed into the cult and the guards will dissipate.
Wait until it's a handful of people and kill Harrow. Loot him and get all your stuff back. Now grab the book and fight your way through the whole dungeon. Some cultists will transform and melee you, fight them to the death. Others will be wussy spell casters, with enough damage they will turn and run away. Fight through and loot everything you see and you're done with the Dagon Shrine.
Brute Force Method
As soon as the first cultist turns to unlock the door kill him and loot his body. You'll get a key to essentially the whole place. In the next room Harrow will attack you, defeat him as you see fit. From here on you'll just be clashing with guards and fighting your way to the inner sanctum. Mancar Camoran will still flee into his portal and you'll still have to steal his book and fight your way out.
Paths Diverge
Once you return to Cloud Ruler Temple the main quest splits into two main quest lines. The first is helping Martin collect the items necessary to open a portal and chase Mancar Camoran. The other quest line is a race to prepare Bruma for a full attack from the Daedra and saving the city (and Cloud Ruler Temple) from destruction.