That was super enjoyable! The dialogue was hilarious. Reminded me a little bit of Douglas Adams writing style. (And I love his writing!)
The third? fourth? level was definitely the most challenging - the one where you have to jump up a couple times first while collecting a blue and purple crystal. Maybe that should've been the final level. The rest was pretty doable. I really enjoyed the mechanic of "hidden" rooms/gems. Reminded me of Wario 3, which I played quite a bit on my gameboy back in the 00's :D
If I were to give you some feedback it would be to definitely maintain the dialogue. I didn't care too much for the crystals and the specials, it's mostly in the dialogue, finding the hidden souls in the secret rooms and opening the portal to advance. Maybe up the soul requirement for the portals to open so that you're forced to grab more of the souls.
And maybe (going by the wario 3 analogy from before), set extra portals in a level that you can only open with more souls and would require you to go back to previous levels after gathering more! But that's a whole other development path surely.
Thank you for a very pleasant experience! I'd read books of the writer if they-d have any. 