"Bonus minigames" refers to additional small games or activities that are included as a bonus or extra feature within a main game or software. Full definition
Play bonus minigames like mahjongg, hidden object scenes, and jigsaw puzzles. (absolutist.com)
In this game, it hosts Thwomp's Backroom Ball, a series of bonus minigames. (mariowiki.com)
To name a few, you've got Coney Island, Hotel Goomba, Triple Jump, Heat Stroke, and bonus minigames like Ice Hockey and Card Party. (mariopartylegacy.com)