I know this is a prototype, but I think your name could be more expressive of the content I'm going to experience. Names are an essential way we interact with media, and coming up with even a functional name ("Masocore Puzzle Platformer") is valuable design work, which will give your audience a good idea of what you're trying to convey, and internally give you a way of referring to the game without "ownership" - "this is XX's prototype". I'd challenge you to come up with a more creative name that just a functional one.
It is very easy to make the game reset itself if the player is below a certain Y-value. This kind of quality-of-test changes are important to identify and add to prototypes that are going out into the world - they show polish as a designer.
The fire puzzle is difficult because of the way your implementation works, not because of a legitimate player challenge - it was long after I knew what I had to do that I was able to do it, and it wasn't based on learning a skill.