I was thinking about this from your announcement.
I think I pictured it as something like the old caves from lufia 2. You always start at level 1 with no items and equipment. You find items and equipment which can be used during that run. You find special chest with items that can only be found there, which stays with you permanently and can be taken with you in future trips.
Also when you reached a certain floor you would find items to allow you to warp out with your special treasures intact. It went floor 100 with a boss there. Then continued to 200 where you could choose from wishes.
I know this is backburner, but just throwing this out there.
By the way I took a break for awhile and have started playing again. The game is awesome with all the changes and added content. This is such an excellent outstanding game!