its like dragon's lair
you know this game, dragon's lair by the animator don bluth? your animations are like dragon's lair. highly detailed animation of walking, drilling. taking lots of time for each sequence to end. probably maybe its your game mechanic to deliberately make the drilling animation to be painfully long.
also in dragon's lair, the game is super strict in its collision detection. same like your game, where you precisely need to be in the center of the boulder to push it and so on.
put all this factors in and boss levels that need super precision timing and pacing makes this game really really frustrating. I stopped playing after winning the second boss cause it just grits my nerve on how precise the timing is needed to escape from the lava.
hit a wall for a second? guess you can kiss your ass goodbye as you have no more time to escape from the lava.
puzzle games with such precision and speed factors just don't make a good game at all.
props for the don bluth animation of your character sprite though. could had use a frame or 2 lesser.