Very cool overall (concept, music, skills)
My complaints are that the ending is pretty underwhelming. Especially since stage 18 looks like our sky, so I thought "wow, is he falling from the sky on Earth? Is he falling FROM hell? Or is he going to reach hell after passing through the Earth's sky and ground?". Then what is got is freaking fireworks. O_õ
Come on!
And the other complaint is the apocalypse mode. Generally this kind of endless mode is good for the player to test their skill or builds. But there's no way to avoind those monsters without using skills and I couldn't even chose my own combo. So it was just blasting through enemies repeatedly (while blasting my ears with those sound effects), which got boring after a few seconds
But great job anyway!