when the player shoots rocks (or possibly other non-player entities) there should be a responsive feedback such as explosion effects or screen shake. anything from the player getting hit to them teleporting across the screen can count as "stuff happening". correct use of colors can make a huge difference here aswell.
and also adding a scorecount that counts up in a cool way would improve player experience. numbers getting bigger has a very satisfactory effect on players.
when the player shoots rocks (or possibly other non-player entities) there should be a responsive feedback such as explosion effects or screen shake. anything from the player getting hit to them teleporting across the screen can count as "stuff happening". correct use of colors can make a huge difference here aswell.