5 suggestions:
1)Add vertical movement contols (ability to move up and down) to Free camera mode, because after having such controls in other games with 6 degrees of freedom not having them is inconvinient (R + F, Shift+Ctrl. Shift+Space or Ctrl+Space would probably be good key combinations).
2)Add collision detection to Free camera mode, so that you won't clip through textures while trying to explore finer details of the fractal for example.
3)Make Zoom to scale combinable with Free camera th make it more convinient to explore the fractal .
4)Add some sort of information about the existance of cheats and how to activate them into the game.
5)Maybe make it so that you can make ball teleport to camera's position when you exit Free camera mode.
(If any of these features are already implemented then i couldn't find them)
Also on PylonPalace level i had a few moments when i had elemets of the level apear between camera and the ball, so maybe make it so that elements of the level become semi-transparent if they appear between ball and camera.