Very interesting concept and it gets surprisingly difficult very fast! I agree with the suggestion on having some videos or a short tutorial to teach you how to play, instead of an instruction page. There were also some issues with the UI in general as it was right up against the edge of the screen, and gets cut off when the game is not full screen.

I feel like there definitely should be some background music, and also some audio/visual cues for when a stone has been "zapped" successfully, as it wasn't always obvious.

i got great feedback from you on my game and I try to give a little bit of that back. your concept is super interesting. but i had a hard  time understanding the rules of the game. two ideas on how you might improve that and make your game easier to grasp:

2. a gif or short animation at the beginning showing how to correctly zap a stone