The combat system is great, I especially liked the plunging attack, it felt really good to bounce off of enemies.
The feedback (both white flash and audio) for hitting enemies and animations felt good and made the combat feel really fun.
I also enjoyed the idea of using blood both as health, as a reward for killing, and as the main story progression method.
I think however that it just increasing the numbers would really help (multiply both damage taken from enemies and blood gained). Since it felt a bit slow to start with 100 health and then fight enemies for a few more minutes for 50 more.
I agree that the story needs to be fleshed out a little more, it sounds interesting and I was missing some motivation for playing, especially since it was always the same enemies and they were fairly simple (and the bats stopped attacking me at some point).
The visual style is really cool and I like how it was very minimalistic but polished and everything fit together really well.
Looking forward to seeing more in case you end up updating this!