I think it’s be fun if we challenge each other in trying to do things that could be useful as solutions in real life games.
Ok, here’s mine, I had some fun today in setting this challenge to myself and overcome it.
You have a 2D game, with the main camera set to orthographic, but you want to present the player, when he enters an options/inventory/whatever menu UI, with 3D windows/buttons/objects (so they can be rotated along the X or Y axis).
Of course, the menu UI is superimposed to the game window, it’s not a separate one.
I’ll leave you to it with a hint: you don’t need a single line of code to solve this problem. And try to have some fun while doing it, I’m eager to read some answers and how you solve this puzzle. 