I know what you're talking about, but it's just not my cup of tea.
'> For me, stairs are much more elegant and elven. I imagine them living in harmony with nature anyway, so that animals wouldn't be a problem. Sorry, not trying to be negative - it's just my personal taste.
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Also, I think that the main advantage of an elevator is to allow transition from a walkable lower area to a walkable higher one without having to worry about walkmesh, but there's no walkable lower area in this set. That is by choice. It's a walkmesh nightmare anyway. If you want to have houses amid trees on a "ground level" and also houses on upper platforms, then they all need ways to walk around, and they just get in the way of each other. (Or, sometimes, you see blank forest floor "walled off" for this reason when there's walkable terrain high in the trees, and it always breaks my immersion.) The only way I think would be properly workable would be if a tileset with upper and lower would-be-walkable terrain was duplicated, one having walkmesh for the lower terrain and the other having walkmesh for the higher one. It would mean an area transition with every change from upper to higher, though.
Sorry, think I went a bit off-topic from stairs and elevators there!