Viewfinder is a new 3D puzzle game on PC and game consoles. It involves taking a picture with a film camera, then using the 2D picture to overlay the 3D world. The 2D picture then replaces/augments the 3D world with the 3D that was in the picture. It’s hard to describe, but very interested technique.

There’s also folks like Willlogs who are making their own versions in Unreal and describing how they think the mechanics work.