What is "Ingress", the real world smartphone game?

What is “Ingress”?
It is a location-based game for smartphones that uses augmented reality (AR) technology. Since its official launch in 2012, it has become available in more than 200 countries and regions worldwide, and has been downloaded more than 20 million times. The game is developed and operated by Niantic, Inc., a company that became independent from Google in September 2015, and amazed the world with “Pokémon GO”.
Ingress “Agents” must choose to align with either the green “Enlightened” or the blue “Resistance” faction and become involved in a territorial battle over bases called “Portals”. Ingress uses real world map data and the Portals are set at real locations, such as shrines, temples, historic spots, and works of art.
By capturing Portals and linking them together to form a triangle, a Control Field (CF) is created and Mind Units (MU) are earned. Capturing these Mind Units for your faction is the basic goal of Ingress. It is the combination of both a territorial battle and location-based game.
However, there is more to Ingress than what appears on the surface. Elaborate characters, cryptic puzzles, and an evolving narrative based of the actions of real Agents combine to captivate Agents all over the world in a game unlike any other.

Ingress portal site address