Single-Stack Solitaire should be 1 star. I’m really not sure why it has 4 stars. It is trivially easy to complete, only marginally harder than Hanoi Solitaire.
Edit: Hanoi Solitaire got updated and I see that there’s actually a restriction on how the stacks can move. That means Single-Stack Solitaire is actually far easier than Hanoi Solitaire (which really should be rated higher now, unless I’ve missed something in the short time I’ve played it). It’s unironically the easiest one I’ve played. Single-Card Solitaire, Binary Solitaire, and Tabula Rasa Solitaire (which also has 4 stars, somehow?) are all also trivially easy, but they at least require some degree of card management to ensure you don’t get stuck. Single-Stack Solitaire is pretty much impossible to lose no matter how sloppy you are. Just follow the below image. Put a QK of different suits on top, and then stack A to J on the bottom.
