What does it take to build a great AR experience? That’s the question we asked ourselves when creating a new augmented reality app for MWC Barcelona (formerly Mobile World Congress). To celebrate Android’s annual Partner Walk scavenger hunt, we put an AR-spin on what’s become a beloved tradition. Rather than search for enamel pins as in years past, the app prompted attendees to roam the event collecting life-sized animated AR characters, further enhancing the experience and improving engagement.As you think about how AR can help you with your next design project, we wanted to share some things we learned from building this experience and watching people use it in the wild.Download the app to try it for yourself, and read on for our tips.1. Test your assumptionsA seemingly simple interaction of “scanning” a floor decal and looking up to see an entertaining 3D animation is surprisingly difficult. Breaking down this user interaction, it actually includes a lot of parts—like the physical design of the decal, all the 2D UI, and all the 3D AR elements. We discovered that people continued to look at the floor decal unless there were multiple AR elements, like an animated dotted line, to assist the user to pan their camera phone up.2. Make it usefulThe pin hunt gives attendees a goal to find all the partner booths in the cavernous halls of the MWC conference. As we thought about the AR companion to that experience, the problem became clear: How do we point the person to the next partner booth? This question is one that AR is uniquely equipped to solve. We took some lessons from Google Maps to help us design the scavenger hunt’s AR elements. We made each floor decal unique; scanning one would tell users where they are in the Android Partner Walk, and enable us to point them to uncollected pins nearby.3. Bring delightIt was awesome to see MWC attendees’ smiles and surprise when collecting their AR Android pins. These were people in business suits, roaming the show floor between meetings, engaged with a collection experience where they were willing to walk long distances to complete the challenge. We put a lot of care in developing the 21 fully-animated 3D scenes and were glad people enjoyed them.4. Be responsiveOne of our biggest worries was a user pointing their camera at the floor decal and it either 1) not triggering at all or 2) unresponsive for an unacceptable amount of time. Anything over two seconds starts to make users question whether they have done something wrong or whether the app is buggy—both are poor user experiences. Related to responsiveness, we also felt that these AR collection interactions should be short and sweet. We wanted the attendees to see a delightful Android, collect it, and quickly orient to the next booth to visit: all in under 30 seconds.5. Learn from your mistakesLike any project, once it’s in the wild, you realize some things should have been done differently. One lesson is that we should’ve made the floor decals much larger. When placed next to our office desks, they seemed huge, but when placed in the Fira Barcelona conference hall, they looked quite tiny. Lesson learned! For future projects, we’ll be sure to test physical elements onsite.You don’t have to have attended MWC to experience this app for yourself. Download it now on your ARCore-compatible device and play around with placing the animated AR pins anywhere you like.By design director Joshua To and designer Steve Toh of Google AR/VR