i had an idea id like to throw out into the wild, feel free to shoot it out of the sky (this is a pun but only if you read everything)
I feel like getting wings as a succubus is a little underwhelming, sure grave hands and the harpy tower allow skipping the check but that feels a little... little...
the game mentions succubi and incubi flying in and out of the tower, and Rinni also mentions that they fly with a combination of floating magic and the use of their wings, magic Rinni could teach the player after becoming a succubus
imagine having a fast travel thats based on flight where, you go up a level and you can fast travel to and from any open air section of the location youre currently in, but these places are displayed on the game board itself sort of representing their basic locations relative to eachother (the levels of the tower in this case can be displayed in the same direction as north for that specific circumstance) with reactions from some npcs as they dont expect their good friend the lust doll to come barrelling out of the sky (maybe add a bit of humour if the player isnt nimble enough the landing is rough)
The flying layer of the desert could have a single square representing one of the grids, with oases being bluish squares, and the various already discovered locations marked
furthermore another higher layer could be added for the general locations of new-ark milk farm and whatnot, which will allow the dev to build on the worlds location positioning
also landing in upper new ark should be impossible for some reason, either the guards detect an unregistered intruder or theres aerial defenses