Started up with a new character, a Breton with custom Dark Mage class (main magic skills Destruction and Alteration, advantages 3x int in spell points, resistance to shock, immunity to paralysis, rapid healing and only disadvantage is being unable to use magic in daylight - this kept leveling difficulty low, while still having good bonuses). As starting spells I've got Shock, Slowfall and Chameleon. Knowing the layout of Privateers Hold (starting dungeon), and combining ebony dagger with shock I quickly cleared the whole dungeon of enemies and loot, and also advanced to 2nd level. Then I moved to Wildertown, one of the bigger cities, sold the loot and signed up for mages guild. As a first quest, I had to enter The House of Vladingus dungeon, and kill crazed mage Belladayne Gaerslay. Travelling by daytime, I had no mana, and entering the dungeon I had no place to rest and regenerate it - the whole dungeon was swarming with rats, bats and nightblades. Wandering the dark corridors I occasionally heard screams of skeletons from the upper levels of dungeon. After a good while of wandering, I reached the mage and slain it with my ebony dagger, which I used to clear most of the dungeon due to lack of mana. Then I ran to the exit, and checked the loot - some armors took from nightblades, lots of books, ingredients, holy tomes and holy daggers, an enchanted talisman with open spell - wih lots of dunegons having locked doors it's a mana and weapon (no need to bash when everything else fails) saver, and some clothes. The loot was worth over 4k, though merchants lowered it down to 2k. I kept the talisman, and as a quest reward I've got steel gauntlets with Feet of Notorgo spell (fortify speed), which I kept with me too. Dungeon crawling well done.
The Elder Scrolls II: Daggerfall, where not getting lost in a labirynthine dungeon is already a huge reward.