Took me a while to get to play this. A truly neat thing, although felt somewhat short and easy at times. For anyone wondering about the "invincible" mid-boss fight, it is very easy (although very unclear): although the boss shows no damage blink hinting you one will not receive any actual damage, he is a classic "escapes when hurt too much" boss, so just keep hitting him as hard as you can no matter what (takes somewhat a few hits if you have a high damage skill) and he will flee without bringing too much trouble, if any