Ingress (also known as Ingress Prime) is an adventure game that uses your smartphone's GPS to locate you in a game world that correlates with reality. You interact with virtual "portals" located near statues, monuments, civic and historic buildings in your real world. They act as

You play as a character in one of two factions (the green Enlightened and the blue Resistance) who are fighting to control a new powerful technology. The Resistance sees it as a potential threat and the Enlightened want to embrace it.

Play is similar to geocaching but with a tactical capture the flag element. You use a game map on your smartphone screen to find and coordinate takeovers of enemy portals with other players. This is done by walking, biking, or driving, to within 40 metres and "hacking" it by selecting this option on their scanners. There are specific missions to visit specific places in the game world (by going to the correlating location in the real world).

This basic set-up sets the scene for complex and co-ordinated player tactics, as well as a plethora of other strategic items to collect and levelling up. It's an unusual game for its real-world movement and travelling.

The mobile app has been downloaded more than 20 million times worldwide as of November 2018, and led to a hugely popular series of games:

• Ingres (2013)
• Pokemon Go (2016) on iOS and Android
• Ingress Prime (2017) on iOS and Android, updated with a superhero aesthetic and story.
• Harry Potter: Wizards Unite (2019) on iOS and Android, with a Harry Potter theme.