You should be able to pull vertically by pulling it from above or below, but if you pull it from the side, then is just horizontally.
It's easy, to be honest. :)
I created a script to save a number after each completed level, representing the next level to be played. If greater than 1, the Continue button is enabled and loads the correct level. To save, I write in a file in the path user://[name].[extension], this creates a temp file in your browser where I can load this info later, if needed.
Lastly, thank you for playing and for the feedback! :)