Another Course

Very simple when you find it, but I don't know why the original slider can't be moved at all

I'm sorry, this is my first "poor" rating. It's nice that you thought to modify an original level. It's just that there is no real game play here.

Spoiler: Sole mechanic

It's fairly obvious that there has to be a hidden slider right where it is. Then it's just a pain to move it as its handle is not visible. Similarly, leaving a draggable with a handle exposed that is in fact not movable distracts from the art of the level. Better to allow it to be movable and just not serve any purpose in completing the level. In the future you can hide draggables in the shadows or partially obstructed. To improve this level you could also create some alternative false paths to the end button to challenge the player to find the right one.

I hope these comments find you in good spirits and encourage more levels.They are not easy to design nor craft. Thank you very much for your efforts!