The ability to subtract mass is definitely needed. All you can do is click “undo” and try again. You can drag the holes around too. Still pretty fun, I played 5 or 6 levels

I just pushed an update. Click on the hole and controls will appear. I think you'll enjoy the later levels (10+)

Nice domain name

Thanks. The important context is that I am 6ft 7 (and once knew all the words to Hypnotize)

Tap the black hole and it gives you ability to add and remove.