This game was pretty fun to play, absorbing your enemies and getting more powerful was pretty fun and made me feel powerful! For feedback I think you should put a cooldown on firing (Spam clicking is very powerful lol) and give feedback for when the player is hurt (Maybe sound).
I would suggest that you can become immune for a couple seconds after getting hurt maybe so you can stay in the game longer! (And can only lose 1 life at a time)