Overall great look and feel and it matches the theme well.
Few feedback elements : Make the spikes more noticeable somehow, I died 3 times before I even noticed them , I thought I was just being teleported somewhere else ( or add some death sound or something ) .
Maybe make the character disappear when it goes " through " a door, so we understand the changes, as sometimes it stays on the same place, sometimes it moves but that's minor.
Well done !