I've seen some great resources here about creating beautiful maps, but what about designing puzzles? How do you even approach designing something that you yourself should not be able to easily solve?
I've found one great video series, starting here: https://www.youtube.com/watch?v=4YpQVdZOjgI
Curious if others have any more input or resources.
Mark Brown's videos, especially the Boss Keys series, are also useful.