At first I thought the game is broken, I was going to leave the comment that I can't start it when I press the mouse on the "START" button, but pressing space worked. Not sure if you intended it that way, but if not it's probably some UI element blocking mouse events.
Game itself is nice. Art and music are great. I was getting lost in the big open world :) Perhaps changing top indicator flash frequency as you get closer would help - but that would take longer to implement of course.
Ranged enemy got me, I couldn't get past it :D