Well I think you aced the psychedelic aspect of the game!
I would suggest maybe some form of controls screen in the game though, since the only way I could figure out how to actually progress was by looking up the controls on the game page. I haven't played Boulder Dash or anything like it before so I guess what is likely obvious to others was a bit of a subversion of expectations for me. I kept trying to enter the castle door lol.
But I still thought it was pretty fun, nice work!