The art direction for your game is fitting for a game about vampires and undead, especially with the dark tones and bright red blood packs. I got a Dark Souls vibe from the armored enemies, which looks really cool, and I think it would be neat if they were more dynamic and had more movements and/or attacks. The soundtrack to the game is very pleasant, I hardly noticed I had left the game running in the background for 10-minutes, and I was just subconsciously jamming out. The game loop is very satisfying, and the levels last for a good amount of time for the fast-paced gameplay that comprises the game, and it also gave me a perpetual sense of achievement every 5-10 seconds. I noticed that I speed up how fast I press the keyboard to move my character after getting to a new level, as if I feel my character is more powerful from having defeated previous levels. It's a bit like an adrenaline rush. The game also lends pressure to the player when they're playing, because I didn't want to lose after being on a streak for a long time.
I think that the bat transformation is a neat mechanic that makes the gameplay more dynamic, in that it gives you additional ways to avoid obstacles. I could not figure out whether or not there was a penalty for going into bat mode, but it did feel a bit overpowered because there was no perceived consequences for it. The textures for the tree obstacles were a bit difficult to see because they blended into the terrain since they were a very similar green. I also don't quite understand how the blood meter functions, and how it might relate to exiting the level. I'm pressed to figure out if there is a consequence for exiting the level without first collecting all of the blood, because it seemed like my blood meter would jump around sporadically after the end of a level regardless. I actually am curious what a longer level may look like as well, maybe even with more complex puzzles and a slower horde.
Thank you for sharing your game, it was fun to play and I look forward to playing your final version!