Very simple but well polished. A good approach to designing a game for a jam! I didn't really understand that the humans were picking up the amulets at first or what my objective was other than squashing them, but I was able to understand after the first round.
The ultimate ability often felt like it caused more harm than good because of the long delay, maybe giving it the effect of stopping other humans on screen from moving with the rumbling would have helped, or at least making it something the player has to activate instead of it happening on the next drop no matter what.
Regardless it was a fun game, very well done!