Really cool game, the art looks really great! Some western background music would have been the icing on the cake. The knockback is an amazing way to move. Just two little things that think could be better.
First, the world doesn't seem limited, if you don't want the player to move too far away, how about a fence? I think that would also look cool with your art style.
The other thing is a score system. Right now you just try to survive and there doesn't seem to be a goal.