This feels so good! (except just i expected arrow keys to work as well)
I like look of the cave and ghost.
The idea is cute :)
I'm going to chime in here on the controls as well. I agree the arrow keys should have been an option, but there's a more subtle issue with the controls. The hand/hands (depending on how you play it) have mixed "responsibilities" that make it more awkward than it should be to coordinate. With the WASD/E/Space controls you're either using one hand, where that one hand is doing _everything_, or you're using two hands where one hand is handling movement and switch, and the other hand is managing (optionally) jump and place. I'd have to go read the research in more detail, but I believe this adds cognitive overhead to the control scheme. Also, by doing this it means the "movement" hand has to keep moving off the movement keys (occasionally needing to reach the "switch" key). There's not a lot of inputs required for this game, so it would be easier to be able to leave one hand on "movement" and one hand on "actions". Less travel, and less effort trying to make one hand manage different types of actions.
But other than getting me tripping over my own fingers trying to coordinate the place/switch/jump chains (and often failing by hitting the wrong button at the wrong time), so far so good!