First-person puzzles. The taxonomy here is broad and I'd say questionably angled. Anything that sits comfortably in Myst's legacy is appropriate, but puzzling as mechanized interaction is more or less a requirement, which means standard walking sims don't necessarily fit.

So it's wildly subjective. As an example, I don't think I could mount an articulate defense for Outer Wilds or Tacoma being in this crowd, but it feels right to me.