fun demo and i only played a couple of mins but i have some fundamental issues with it: 1) enemy health bar should not be on the same line as the player's which obscures it, 2) when jumping to the platform with the potion, you fall thru the left-most tile which is misleading as you cannot land on it as expected. after you do collect the potion, you can now stand on the tile. if this is by design as some sort of "trap" or illusion mechanic, i can understand :), 3) adding arrow keys would be a plus and at least an alternate keyboard key used for attack is better than having to LMB, 4) the text is quite small and hard for some of us to read.
a lot of potential fun so thanks for sharing and my hope you'll continue development :)