Not a bad concept! Reminds me of games like Bit.Trip Void where growing larger is positioned as both a good and bad thing, and spamming the shoot button when I grew super large was pretty entertaining. I'd say my main issue was that because of how quickly you grow and how little of a threat the enemies are, the game gets really easy really fast. There was also a point on my first go where it seemed like enemies just stopped spawning, and I just ended up dying from flying my blob off the screen while trying to figure out what to do. Still not bad though, I see what you were going for!