Really impressive submission. Found myself too engaged to stop .
In the description it suggest that you want to build atop of this game, i would suggest a better height view using the right click (show more height numbers around the clicked tile, or nearby differences, or something like that. As it is now it is easy to lose sights of the height and reading the height one by one is not user friendly).
But this is just an idea. Otherwise this is totally above avarage submission for a jam. Good job!!