Agree with the previous comments! As a prototype, this is very good! Clear instructions, eminently playable, even relaxing (which, if that's not what you're going for, maybe consider some of the other suggestions!) I finished with 5 seconds left, and I was meandering. And the timer is pretty high to begin with, so it left me wondering if that's the feeling you want to create. One possible way to frame this is to have an unlimited timer but have time goals (e.g. bronze, silver, gold), so that I don't just get reset when I'm about to finish (I'm assuming that happens, but I didn't actually check).
I definitely prefer the experimental version, even with the weird camera issues, because it addresses one complaint about the standard version, which is that it's very hard to understand where to go next, especially in more spacious areas (I'm thinking specifically of the area just after the maze). In the standard version, having an object attached to the camera that is always pointing towards the exit would be helpful.
Some feedback on project organization. Generally good in the project area, but I'd definitely suggest clearer naming of objects in the hierarchy, and maybe even some object grouping via empty game objects (you can really treat them as folders). Keep in mind when doing this that objects become positioned relative to the parent, but as long as you do that you'll be fine.
Finally, a question: In the experimental version, the horizontal movement of the camera is bonkers fast when the ball is not moving, or moving slowly. Why do you think that is?