I'm seeing a lot of overlap with the "No Undos" and Any% categories. I tried messing with the Undo button and couldn't find much use for it as a semi-casual solitaire speedrunner, since it's not like some hint or skip button which can always save time. Is the Undo button a viable strategy for more competitive runs? If not then I think it'd probably be best to merge them.

I could be wrong about this, but I think solitaire rankings started a tradition of considering the undo feature as cheating. It's not explicitly stated but I think runs that use undo might even still get rejected from the windows solitaire categories. I don't know if it could possibly optimize the game over not using it, but it can be used to save a potentially very good game.

I don't really have an opinion either way, going for a good game and realizing you need to use undo pretty much means the run is dead for me so I'll probably never submit a run that uses it.

I'm thinking whether or not a run uses Undo could best be tracked using a variable instead of a sub-category (similar to Microsoft Solitaire's "Vegas" variable).

yes i have used it to save runs a few times but it is more f a last resort for me I think it is just another variable