Wow amazing how much you were able to produce!
Very nice mechanics and implementation.
One thing I felt while playing was that I sometimes could just trick the level, like not needing to unlock one of the doors in the last level. Like there were many ways of solving each level. I haven't thought much about puzzlers, but I think maybe the level of satisfaction is higher if there is one single solution? I'm not sure!
Maybe the protagonist could have respawned automatically when he touched spikes too, not sure.
But all in all, amazing entry. Very impressive!