In this puzzle, the only way for anything to move is independently, and everything is free to cross anything else.
This kind of blocks the notion of a "difficulty curve" - it's just a flat line.
Level 4 is different, but I'm guessing the reason people say it's easier is that the frogs on the left never need to interact in any way with the frogs on the right. You can just march your left-frogs onto the transformer, see them turn around, and march them back to their ultimate destination, then repeat the process on the right.
I don't think there's any solution that would allow a frog to jump over the transformer, so you're essentially required to do this - all frogs must make their way to the transformer, transform, and go back home - although you can make it look more or less complex. This essentially gives you two copies of the "level 3 and below" puzzle, one on the left of the transformer and the other on the right.
It would benefit from that model that is popular nowadays whereby higher levels are unlocked by solving lower levels, and you can choose to play any unlocked level whatsoever.
But now I think a roguelite version of this game could be quite addicting.
Years ago I wrote some example Python to solve the same puzzle in another game (with spoilers for level 3):
https://sheep.horse/2011/11/jumping_frogs_-_using_python_to_...
A great introduction to the Scientific Method, and a fun activity too.
Here's an example: https://spiremaths.co.uk/wp-content/uploads/Frogs.pdf
Quite cute diversion.
Did I mess the direction or is this by design or is it an omission?
