Can someone give me some assistance. I want the page for Noita to be like the pages for Teraria or Factorio where there are "category tabs" at the top and "selector" refinements under each. 

I claim, I am not so dense, but I can't quite intuit or search out the answer to this.

Thank any in advance.

Those are variables turned into sub-categories. There's a toggle in the variable tab for that!

- Go to edit game
- Hit the tab: variables
- Hit 'New variable' and give it a name
- Add new values underneath this variable like 'Easy' and 'Hard'
- Check the default value
- Now click on the dots next to the variable and hit 'Edit variable'
- Now switch 'Use as sub-category'.