good Puzzles and level design 
If kids plays these kinda games, They will be happy and also learned studies!!!

Can you play my game!?!?

Good puzzles, though the ones with reuseable operands are much easier.  For any two numbers X and Y that are relatively prime, a solution exists for value Z where mX - nY = Z (If you have a reusable adder and a reusable subtracter, and they don't divide by the same number, you can get literally any other number.  It might take you a while, but you can do it.)

It's an interesting idea, could be a fun educational puzzle game with some polish. Nice work

Nice concept :). Biggest issue for me are levels that can be solved by just using + - blocks.

I could somewhat cheese some of the levels by just standing in front of the right + or - machines. Neat little block pushing game though

Sometimes the math would be incorrect, but the door would still open. I like the idea behind it though!

Ran into an issue where after 6 levels the audio cut out and I couldn't restart the level