If you have ever played RPGs (Role-Playing Games) before, you would know that the act of “leveling up” often requires defeating the same monsters over and over again in the same stage for hours on end. Even mobile games like Candy Crush or Angry Birds require the same repetitive action (bird-throwing and gem-matching) for weeks or months in order to level up and progress. In the gaming world, this is appropriately called “grinding,” and it is fun and addictive for children and adults alike.
