Great idea, I really enjoyed hitting enemies with the swinging ball, was really fun launching it back and forth between enemies. The walljumps/platforming was a bit clunky though, the character is too fast I think, maybe make him slower?
Another big thing is enemies attacking you offscreen, it's a bit annoying and I think maybe unintended for enemies to continuously attack you when they're too far/are not on screen. This might be fixed if the camera zooms out when an enemy starts attacking or make their attack range half of the camera's width/height in order to ensure the enemy is in view when it is attacking.
Otherwise it's a great game and a really cool mechanic.
edit: also the music is incredibly low volume compared to the other effects in the game.