This is awesome! The premise, the graphics, the music, the sound effects, the level design, it's all here and all masterfully done. I let out an involuntary cackle the first time I heard granny's death screech on some spikes.
I made it all the way to the last beatable room with the bugged blower per the comments below, I thought I was going to rage quit quite a few times earlier but the game somehow keeps you gripped in by granny's bony fingers.
One of the most mind-blowing parts besides the excellent presentation was how the level design leads you to the next challenge perfectly, adding just enough in each previous checkpoint to help you figure out how to solve the next one while keeping up a constant level of increasing challenge. Swinging the blower back and forth to dash and jetpack is a very satisfying gameplay loop.
This could definitely be a hugely popular speed-running game. It felt like I had paid money for it, it feels so complete. Oh and lastly I have to mention that amazing menu nagivation where granny pushes the buttons for you. Amazing work, what a masterful team behind this game.