I had a hard time understanding what to do at the start of the game, I think because the green square wasn’t immediately obvious as a source to me. I picked up more of the mechanics after a few more playthroughs but never got past the first enemy (all powerful plumber rat) ;(
A little more tutorial text would have been helpful, I think, or a tutorial screen. I found the core concept creative though, and would definitely have potential for some interesting gameplay with more refinement.