Thousands of people from all over the world were in Brooklyn on Sunday to participate in a game that entices people to explore new places.

Ingress is a free mobile game that people can download as an app on their phones.

The object of the game is to discover and capture "portals," which can be art pieces, museums, or historical markers throughout a particular city.

The only way a team can take a portal is by physically visiting the landmark, and claiming it in the app. The game took place in Brooklyn this weekend, pitting the green "Enlightened" team against the blue "Resistance" team.

There are no cash prizes in the game. Competitors play for virtual medals.