Simple idea but great execution! If your idea with the shifting numbers was to keep the player constantly having to re-find the next number, it worked really well. I found it a bit disorienting initially but realized that it was probably to prevent people like me trying to remember where I last saw a number.
One thing that I found could be a bit improved was when a the auto-break the next number activated, having a different sound to the regular block breaking would've been nice. A few times the auto-break activated at the same time as me breaking a block, and I didn't realize it'd happened so I kept trying to find the number the auto-break just removed.