I am not actually certain how they did it.
But- I think I have a system worked out now for how I can do it. Essentially, I 1st draw some terrain. The I edit it in particular places so that the player could not possibly cross it. Then I sit there for ten minutes to a few hours (depending on how tough it is) attempting to believe of a way across that utilizes the games features.
This can get a bit risky although. Any inventive sparks inside my noodle have to be tempered with the line "How significantly further operate is this going to be?"
Then, any tips I have that are also comparable to prior puzzle solutions get the question "How pissed off are your players going to be?" which is often right away followed, "Well, how pissed would you be?"
The answer is practically always a lot.
So it comes to obtaining a balance. Obviously, I can't repeat something (unless I'm undertaking it deliberately) but I also cannot start bringing in tips that are too various without hugely escalating the workload of absolutely everyone on board.
I've lost a lot of paper to scrapped suggestions.