I totally love the idea of this project. Just make sure that the spinkick thing can be consistently done unlike the original version, especially doing it the 3 times in a row (which would be a lifesaver if I could make it freaking work when I want it to)
I say that you can vote for two that you want the most.
Scarlet Devil Mansion Route
Netherworld Route
Eientei Route
Flower Route
Youkai Mountain Route
Underground Route
All choices are <3 but I guess my pick of 2 would be Netherworld Route and... wait, no UFO-themed route choice? D:
Also, while putting in a smaller hitbox then the original is a great idea (Bullets not even touching your sprite yet killing you=wtf.), don't make it a really small hitbox like in the shooters. You get bullet-destroying shot and bullet-reflecting gohei and superpower spinkicks for that. Also, I just realized Reimu's spinkick in the fighting games must have been inspired from tHRtP, awesome.