Played through most of the game. Skipped some levels here and there.
This is an interesting game, it combines puzzle solving with dexterity, which I suffered a bit since I cannot draw a straight line with the mouse to save my life.
I like how the main menu background changes depending on which world you choose.
The levels are very interesting and I and the mechanics were introduced properly. Levels could use a "retry" button. Spamming the undo key until everything is empty works but it is cumbersome.
I had issues with controls like the other posters already mentioned. I will add that having to always click the cube to start drawing is annoying when trying to start a line from the border of a side so it matches a line from the other side.
I know the game is in early development, but the physics in general feel broken, specially with the top face and rotation. Many times I watched the ball having certain motion and switch directions entirely once it switches to a different face. Take for example temp name 7 of desert sector. If you don't add any lines, the ball goes straight down, touches a booster, goes to the top and in a straight line reaches the opposite face where there is another booster. You would expect the ball to return in the exact same direction, forming an infinite loop. Instead it makes a sharp turn and goes to a completely different face. Other instances were the ball slowly moving to a side from the top, the camera switched and it started to go in the opposite direction.
Sometimes drawing a line changes how the simulation plays out in places that don't seem to make sense. Like having the ball land perfectly on a slope and after adding an unconnected line somewhere the ball now bounces.
When pressing multiple times a spin key, the cube will start spinning in the opposite direction, I believe because it tries to latch to the right face index. This is annoying when spamming a key to quickly visualize the entire cube.
Clicking the restart button while the cube is spinning in the test sector breaks stuff.
It was fun, but a bit frustrating at times. It is a real good start and I hope you will be able to develope this game further.