First of all, you did a great job on the pixel art, I know how much work it is to animate a 8 directional character. I love the music and your game idea overall, definitely fits the theme, but I have to admit, that I did not manage to get through the treasure room. Here you have constructive feedback (like you wanted):
- diffrent kinds of gameplay elements would be great, like some interactables, for example buttons or swiches, that activate something. That would courage you to search for more then fake walls and spikes.
- checkpoints (I've read below why you could not inplement that)
Don't have anything else to say. great work :)
(a hint on the treasure room would be nice)