Outer Wilds does some amazing stuff. Utterly brilliant in how it constrains your path through it’s small, polished world, and makes it feel incredibly dense.

Hades is also utterly amazing, with similar attention to repeated play.

Game mechanics is definitely one area that seems to have been lacking.

Aside from that, there's a certain homogeneity to games these days. I think that's attributable to the fact that there are more of them and that to reach a broader audience there has to be some generalization that occurs.

Going 3D is a huge limitation on what kind of mechanics you can do. Decent was reasonably popular, but showed how much difficulty many people have given full freedom in 3D space. Sonic style fast scrolling or precise platforming games really don’t translate well.

VR is even worse in that respect as people get seriously disoriented much more easily.

Going 3D (and HD) also consumes far more budget for art and level design, so companies are less willing to take risks in other areas.