Really nice game, looks very polished in many ways.
took me some time to understand that ennemies spawn when there is empty space off screen, having an empty chunk at the beginning would have help me understand that.
Also, when you start digging in the bottom like me you cannot use your shot gun to shoot ennemies without digging on the side.
Other than this two points the overall experience was really good, especialy on the art and audio which are the two first things that makes me want to play :)
Good job !