This is a GREAT short puzzle, love the concept and want so much more of it.

I have only one thing to complain about: not having the straight lines entering the blocks. That triggers me so much I found a workaround with joints to force them close to the blocks to have straight input lines.

For some criticism/suggestions:

• Maybe demand the player use ALL given blocks as a constraint? Or at least make it an optional objective.
• If a stage has more than one number to input, require a solution for all inputs or have it be an extra goal to work towards.
• A slider to define the number speed would be great.
• The joint is not very easy to know when you are moving or linking, the difference was too subtle for me.
• Don't skip to the next stage immediately, some times you want to share your solution.
• Score based on how many operations (how many blocks got triggered during the run) would be great, even more with a leader board.
• The need to move the number input to load in the machine is... boring, if that's on a funnel and when I press play one input number at a time goes into processing (would be fun to have multiple numbers being processed together).