Formation-I is a small start-up team that I worked with for a few years creating tech demos and trying to get something sticky to launch off the ground in the AR realm. Our biggest challenge was making something AR cool, but accessible to most consumers. This restricted our apps to things that could work on mobile devices like your phone. There are more and more devices coming out with integrated AR support but at the time we were creating these demos only a handful had AR capabilities.
We used Google ARCore, Tango and Unity. One of our first ideas was a geo-location/tagging app that would allow you to tag/locate and navigate to targeted areas around the city. A user could see UI/3D elements overlaying areas around them as they walked through a city-scape. they could interact with these targets and receive information and potentially interact with gamification elements. In our final demo, a user could add nav points from an admin website or in real-space via mobile phone, create navigation, download a navigation file from another device and see real-time AR points be generated, and of course and follow the navigation!
For my part, I worked on the UI and 3D models (3DS Max) that would represent the final "types" of locations (targeted points for navigation like restaurants, hotels, etc. or simply points in pace), animations and testing inside Unity and on devices. One of the challenges was creating several different experiences from different roles. An admin portal to create targets via google maps (instead of requiring a user to physically be at the location), an experience via a mobile device to create custom navigation, and an experience for the average consumer to be able to download navigation or additional information. You'll see examples below of all the interfaces and design work we put together.