This is fun and retro! Reminds me of playing Turrican as a kid!
The sound mixing is a bit uneven, with sound effects much louder than the music.
The intro typing effect is quite rough on my eyes and made me feel a bit queasy. Perhaps because it went so fast and took up the whole screen? I enjoyed the backstory, though I think there should be more actions for the player to take other than clicking through a prompt, especially since it was quite long.
Gameplay feels nice, though I'm not a huge platformer player and if I do play them I use a controller, so I didn't get very far.
The jump feels very slow on the fall and given how fast the fireballs move, it becomes rather tricky to avoid them if you time the jump badly - perhaps that's intentional, to increase difficulty?
The blood UI is too big and takes up too much screen real estate - it overlaps the game arena and blocks vision of incoming monsters.
Great effort and nice theming! Very spooky :)