Great game ! Very little scope that allows to polish it a lot, the base mechanic is well thought and the execution and presentation are top notch !
As mentionned before before knowing you could drag the camera (even though I have read the descriptions for the controls xD) it is difficult to drag your mouse outside the screen, so yea a good solution is to make it more obvious that you can move it (even with drag and clic thith the other button could be a good solution)
Very good job !