I have a Story based on my research, let me tell it to you.
Lately, a report from mobile tools research in 2017, about the popular content on the App market ( both in Play Store and App Store ). Is a Casual Game which is, a casual game is Rank #2 behind Social App like an Instagram or Snapchat but with deep engagement for the Game content and persuasion UX design as a Gamification method to keep the DAU ( daily active users ).
Casual Game rises because most of the User is actually, a non-Game player. They just have a small amount of time to play some Simple, and Fun game yet have a high retention because of their procrastination.
Procrastination is bad from a productivity perspective, but from developer thoughts, that's is a value and could keep or increase DAU and spread the App or a Game.
80% Users in App market have a Simple and Casual thought, they always follow and seek and new App or Game with the biggest Trend ( For the example is a Pokemon GO, many users playing it, just because the Trend. Even they didn't play a Pokemon since Game Boy / GBC in 1998 ). Their perspective is craved several parts for App / Game, Visual, Interface, and User Experiences. And it became a general Trend as a simple design, people mention it as a " Flat Style " but I thought that's just a lazy design without intuitive design ever.
But that's a Market, that's a Niche, and Value needed to convert into Value and Volume and make the profit from it.
Just like Swallow, they just flying ar