Currently, the Symphony Counter level in the alpha is just "Counter, but add 4 instead of one". That is, if the game even lets you place a 16-bit register.

I think this level would be a lot better if you had to instead use two 8-bit registers to make a 16-bit counter. This would add some uniqueness and challenge to the level.
I was honestly disappointed when I found out that this isn't the intended solution, and the game just gives you a free 16-bit register that you didn't make.