[hi19hi19]

Originally Posted by Dinglesberry

That leads me to the question, how are difficulties in stepmania defined? If I saw a song in nuclear blast that was difficulty 15, I'd already know im in for a bad time.. this ones difficulity 16 though o_O Is it just an arbitrary scale?

When you make the file you can set the difficulty to whatever you want.
That said there's a few scales that people use often- I think Mina's scale is the best, which is what I used here (or, rather, what I approximated here, because his difficulty calculator is broken atm), but people also use average NPS or StepMania Leaderboards points or other scales.