Yeah, I personally prefer using the space-bar to the mouse wheel. You can also press the mouse wheel button instead of scrolling if you still want mouse controls. If you can't remember the controls they are in the help pop-up (top right in-game) or in the main menu.
I thought not showing the direction added to the puzzle and planning, but enough people have suggested adding direction indicators that I'll add it. An easy trick to remember is to keep the loops all flowing clockwise.
Thanks for the feedback!