Some things:
- It's very dark and I can barely see anything.
- A checkpoint would be nice at some point because I can't even manage to get the key to the door.
- I will say I do appreciate that a message popped up when I got to the door saying "Find Key" because I would have probably been confused otherwise, but probably because it was too dark to see that it was a locked door.
- Invincibility frames are too short or non-existent -- I'll often get hit multiple times from the same action.
But otherwise good job. Besides being too dark, it aesthetically looks pretty good, and it controls decent too, with already different enemy types with unique attacks and unique hazards all around. It's definitely pretty difficult to make a Metroidvania-type game in 48 hours, so I commend the ambitious undertaking, even if some things can be polished out.