Good idea, however I would have to experiment with building on non-flat terrain beforehand. I've never been a great home builder, so building a house on a hill would be an even greater challenge.
Think of it as an added bonus to your legacy challenge.
Personally I like to start building right in the middle of a hill, so some of the house is in the hill, and some is sticking out in a grand porch. I find starting at the top gives you some crazy porches/decks, but almost a bit silly looking, same with building into the hill.... though the choice is yours.
Though now that you've been talking about it, I want to give it a try myself!!