Fun idea, but not sure what's going on with the aiming. It says it's automatic, but the rockets often seem to be aimed at nothing and then have to circle all the way around while the goblins make it to the basement. Often the goblin is right in front of the character and they shoot in the opposite direction, even when it's the only goblin left. Maybe there's a logic to it that I haven't figured out yet, but it felt unpredictable.
I'm also having the issue of the game freezing when playing again after a game over, but refreshing the page fixes that.
EDIT: Managed to complete the game now and it was fun. I felt like I had to take the firing rate/speed upgrades due to the rockets being so unreliable, though. Once the rares with no downsides dropped, the rest was very easy.