As I've had a few inquiries about this not working on PaperSpigot, I dug around to see what would be involved. After some work TallNether will now work on PaperSpigot. It should work on most branches based off Paper as well with one caveat: if those branches make changes beyond what Paper does I can't guarantee TallNether will be properly compatible with those changes.

I've also added the 'generate-fortress', 'generate-gravel' and 'generate-soulsand' options. As usual details can be found here: Configuration