nice demo , i liked it but had to give up on cave 1 level 8 - there was a jump required that i just thought was just too hard to do after fighting through all those enemies ...
the thing that i found the hardest overall to get used to was the player sticking to walls (and sliding down) without any key input from the player - this lead to many deaths as i would want to drop down quickly while avoiding stuff but accidentally hit a wall and stuck to it , causing many deaths ...
personally it would also be great if spacebar was jump and c or z was dynamite , that would be an easier layout for my fingers !
good luck with it all