That was an awesome game! The main mechanic felt fluid and like it belonged, the slowdown felt well executed (although it can get a bit annoying with the music constantly changing tempo) and combos felt meaningful and satisfying to get, I even got to 21!
Since I always like to give at least one idea of how people can improve, I do think charging in rapid succession felt a tad bit annoying due to how getting to max power worked, and I found combos would occasionally end for me due to me not being able to build enough power to kill an enemy. Perhaps if max power didn't require your cursor to be at the edge of the screen? (I admit my game had almost exactly the same issue xD)
Despite this, the game is really solid, and perhaps one of the best in the jam!