You might think it’s popular because of the brand. Nintendo, which refused to make a Pokémon game for the longest time on a smartphone, has finally caved. But what may be overlooked amid all that is that the game is phenomenally well designed (despite myriad bugs and endless server outages). If you look at all aspects of the game loop — engagement, retention, virality and monetization — it nails pretty much everything on the head. How did Niantic managed to hit a very rare, exceptional home run on every textbook point of the game’s development?