Let's see how long it will take the rest... I'll be content if I complete the game (11 levels left, it seems) under 15 hours total...

Edit: Just last level left.... but 14.9 hours already.... damn, I was close haha.

Completed in 16.7 hours. Last level took more or less 2 hours. A hint: when you reach the 3rd part of the puzzle, do not focus on using the light bridge as a path but as a...... ok, rest is up to you!