For me it’s first person puzzle games. I can think of maybe a dozen off the top of my head that came out in the last decade. I especially enjoy when they’re open world. The ability to just quit a puzzle that’s stumped you and go try something else for a little bit is incredibly refreshing.
Open world RPG? They are probably the most common single player AAA experience released these days. Bethesda does work in a bit of “immersive sim” qualities to their games though, which is often what makes them feel so sand-boxy.