I like the concept and it's cool that you implemented some upgrades for it. It think some of the mechanics could use some polish, though. As someone else mentioned, the pathfinding freezes sometimes which you can abuse to kill enemies. Also, the hitboxes for clicking on rocks seemed really dodgy. I think I was probably only able to throw a rock a quarter of the times I tried.

Neat concept! The enemy pathfinding would sometimes freeze, which made destroying them a bit too easy. Overall nice work :)