The phrase "hidden objects" refers to things that are not easily seen or noticed because they are carefully concealed or not in plain sight. Full definition
You become a digital fan card on the games optional hidden object game. (kickstarter.com)
There's plenty of hidden object scenes, the unique context specific puzzles are still generally pretty fun to solve, and the evidence wall is a neat inclusion. (psnstores.com)
By their very nature, hidden object puzzle games have to keep things relatively simple to allow players to progress. (darkstation.com)