Hi, thanks for your feedback!
I wanted the game to be a roguelike, so that's the reason for no checkpoints. I think if the levels were more diverse, with a different tileset etc. it would be perhaps less frustrating. After death you'd be returning to a level different than the one you died in, so you wouldn't feel like nothing changed.
It might need to become easier though, not sure. I don't think many players are currently able to finish it, even though it's pretty short.