Well, i wont tell the "more" to it, but i will give a generalized depiction of what i cam up with as a quicky way of obtaining the fort.. i never really put a lot of thought into it, however, so i am pretty much open to new ways or complete revision. Of course, actually getting to "obtain" it will be done almost last, as we want quick access for playtesting.
Basically, somehow you hear of the forts location.. havent decided how.. that is still open..
You go to the fort, and you see a mess of skeletal guards that are not aggressive, you walk into the center of the outside of the fort, and are approached by a necromancer.
He talks to you and pleads that you help him, and he seams rather histerical.
He explains some storyline about the fort, how he made it his domain, blah blah blah, and says that while experimenting he found a way to completely control a Lich. He wanted to make the lich super powerful and attempt to take the very soul of the lich or something and use it to enhance his own powers, as it was easier to buff up something else rather than himself to see if it works.
When he discovered how, and did so, the lich was more powerful than he imagined, MUCH more powerful, too powerful for him to control. The lich went feral (i guess we will add storyline about how the lich was the original owner) and now the lich is on the move to attack and kill the necromancer.
Fearing for his life, he used an extremely dangerous and powerful spell to cast the lich leagues away, but the spell cost a huge toll on the necromancer and now the necromancer is powerless to defend himself. He found and trapped every soul he could find nearby, travelers, guards, merchants, bears, wolves, deers, and used all their souls to summon a small army of strong skeletal guards, but he knows all too well that the guards will not be enough at all to take down the lich.
He asks for your help, and after saying "Why on earth would i help a necromancer", or something, he says that he will reward you with unimaginable riches. You reluctantly agree, and he tells you that he needs to do a chant and read a tome of death to undeath to kill the lich, and needs your help to stay alive long enough to summon the strength to cast the spell.
He implores you use the help of the skeletal guards to your advantage, as even though they are by far not enough to take on the lich, they are still strong enough and in numbers enough to disrupt and distract the lich.
When you exit chat, he yells "HERE IT COMES! I CAN FEEL IT GETTING CLOSE!" And then the lich spawns and comes straight for the necromancer. The guards all attack the lich, and you have to as well as if you dont, not only will you DIE, but so will the other dude. From this point it seams as though you CAN kill the lich, after a long battle (and quite a few potions) the lich eventually dies and disappears. You go to the necromancer and tell him that you killed him.
He tells you that you have in no way killed him, but mearly destroyed his mortal body, and the lich will reappear in his immortal form very shortly. If you managed to kill him, then as soon as the lich comes back a cutscene will happen, and you will loose control. (you will be outside the fort at this point and in the wide and opened area) The lich appears, and the skeletal guards all go after him. He casts a spell and all the skeletons are pushed back and die, he comes walking towards you and the necromancer whom is still chanting. Before he can cast anything to kill either of you, the necromancer finished his chant and casts a spell on himself. At that point, the lich stops and a large storm of electricity or fire or something appears and surrounds the lich. As the storm fades, so does the lich.
you talk to the necromancer and he says that he has banished the lich to oblivion for eternity, and thanks you for the help. You inquire about the reward.
He says that he has lived in this fort for a long time, and has no interest in staying in the fort any longer, as the temptation and secrets of the fort are too much for him to bear anymore. He gives you the key, and says its all yours. He thanks you again for your help, and tells you any information you might need about improving the fort, or about the forts history can be found in his bedchambers in a book on a desk.
The fort is yours, and thats where i end this story. There IS more too it, but if i told it would be a spoiler.
This is just a rough, quick thinking way to obtain it, i havent really put much thought into it.