Great use of the theme and a great idea. I think it gets a bit to fast paced. Whether it be increasing the amount of time before resurrection, slowing pausing resurrection timers when in the overworld, or something else, I think it needed to slow down a bit. By the end, I had enemies reviving while I was still trying to kill of the enemies coming in. The symbols on the spirits get a bit cluttered as well when there are a lot in later levels. The idea is so cool and clever though! I think iterating and polishing on ideas here would make for a super cool game. Great work!