It would be interesting to Doue will builds upon the background of the latter [...]
err... what? O_o
No other quests than that one with the purchase. And it won't be a "simple" purchase either - as you will have to spend various amounts of money in different places and advance through the ranks of castle's faction, which will allow you to gain access to different areas over time. Well, at least that is the plan...
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Vac -
Good comparison, though I've seen too many threads complaining: "I have so much money! What I can do with them? Help me!". So I decided to make this "solution", alas not being so simple though...
As for whether it is worth to visit this place, well, the ORE version is more like a demo, a preview to what I have on my HDD right now... but still it contains one or two clusters of those flying particles you're so fond of them :>
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The place is HUGE, and it's only half-done.
Yes, it's not so small, but it's not a huge either... for me at least. The huge (or quite big if you like) is a cavern I did for this castle - http://tesalliance.org/forums/uploads/1295372279/gallery_4163_200_178940.jpg. Four levels high, and with such volume that it could easily swallow all interiors of the castle and still there would be some space left. For reference how small it isn't you have one character on the right side, and another copy of that character holds a torch where that orange light is visible in the middle of the picture. Unfortunately, due to performance reasons such distant views won't find their way into the final version :/