Thank you for your feedback! Yes, unfortunately, I didn't have time to implement tutorial. That was my plan, but because I didn't allocate sufficient time, it didn't make it.
About the ball crossing the line, it's getting a speed boost, when crossing a line at an angle of 30-150 degrees only. Ideal is 90 degrees, where it gets the most speed. It's indicated with SFX and white animation. Otherwise, when in contact with a line, it gets slowed down, which is indicated with red animation. It is good to set up a path, where the ball crosses the lines along the way, to get speed. There's also a soft cap on speed and drag, so you can't gain infinite speed and also can't cover infinite distance without any boosts.