Played this so hard the leader board overflowed lmao (about 2.4 billion)
My suggestions have mostly already been said, moving the camera should be done with middle/right click, and the conveyor belts get pretty expensive. In the late game I ended up using splitters to get things places lol. Sounds can get to be a bit awful in the endgame, so I had to turn that off.
A major problem with this game is it gets to a point where the costs of the building is so high it would take hours for the building to make back what it cost, so you just end up not being able to do anything worthwhile.
I like that you're kinda forced to use all of the machines. When only using one type of machine you hit a brick wall of the price getting up into the stratosphere, so you have to use all the machines to get a high score. The conveyor prices break this though.
Overall, a pretty good game. I enjoyed my time with it. Hope you continue development :)