Solved it! I kept tilting my head because it was hard to see the clue and interpret it at the same time. The ability to highlight all three diagonals would have been perfect.
The final clue I had to complete was that tricky .*(.)(.)(.)(.)\4\3\2\1.*
> I kept tilting my head because it was hard to see the clue and interpret it at the same time.
Agreed, I definitely found myself doing that.
> The final clue I had to complete was that tricky .(.)(.)(.)(.)\4\3\2\1.
Interesting...I think I had the main guts of that one worked out when I was about 1/3 of the way through, but admittedly I did take a screenshot and mark it up in order to keep track of the various possibilities. It was (...?)\1* that tripped me up because I had an overly broad interpretation of its mechanics.
I wonder if it would be possible to record a bunch of 0-100% runs and then to make some sort of visualization to demonstrate different approaches...
The final clue I had to complete was that tricky .*(.)(.)(.)(.)\4\3\2\1.*