You can't copyright game mechanics. So, if you replace the sprites with legally distinct ones and write the code yourself, there are no laws broken.
Actually, you can, in counted cases Copyright Game Mechanics, see: Shadows of Mordor: Nemesis System and Bandai Namco "Auxiliary Games" (Mini-Games during Loading Screen)
Creative Outlets as well as Game Developers could be sued if they made from scratch something remarkably similar to those Game Mechanics