The Verge has a detailed article about this game, Hidden Through Time is a relaxing yet challenging puzzle game.

Hidden Through Time is a game where you locate hidden objects in a scene, similar to 2017’s Hidden Folks, the Where’s Waldo? books, and the puzzles inside the Highlights magazine at your childhood doctor’s office. It’s about as simple as a game could be: it presents you with some objects, animals, and / or people at the bottom of your screen, which you have to locate. Once you’ve found enough of them, you then move onto the next level.

Here’s the trailer.

Hidden Through Time isn’t free, but you can get it for $1.99 on iOS and $2.99 on Android.