Everyone else isn't really wrong, it's a bit hard to play the intended way, reacting in time and aiming at falling rocks/meteors. But it is very easy to cheese it by just aiming in the general direction above you and spam clicking the shoot button. I don't think taking energy to fire would solve the issue by itself unless you combined it with some other change. Maybe if the rocks don't fall but come from the background and get really huge as they become closer to the screen then it would make aiming easy and encourage players to aim and shoot instead of dodging/spamming.
By the way, if you can please check out the game I submitted. Have a great day too!