Hey, congrats on your submission! I think better player feedback would be good here. To be honest, I wasn't really sure what I did. I beat the game but I don't know why other than I managed through a spike puzzle to a flashing circle. I'm not sure what the pickups did or what the key was for (I thought for the chest but the chest seems to open up regardless).
Either way, I think you have a good foundation to flesh out and create a nice little adventure game.