Some suggestions
The game is super fun, and I played it for hours. But, I have a few suggestions if you choose to make a sequel. 1. Don't make the guy's facing dependant on the position of th emouse. For people with laptops and no mouse, it makes things a bit more difficult than it needs to me. 2. The enemies should get stronger too. It gets too easy after just the first upgrade. 3. The drops kind of activate sporadically. Make it to where you get them upon reaching them instead of having to wait two or three seconds to get that needed health boost. and 4, make movement while jumping possible, instead of having to move before jumping.
Otherwise.. KEEP UP THE GREAT WORK!