Thanks to the incredible efforts of Avery and Jessie, we have both an iOS and Android app!
Get the Android app here: goo.gl/35Dv1S
Get the iOS app here: goo.gl/8eCwE6
To use the app, go to the tunnels and look for the mural with the matching icon. Select the icon and hold your phone up to the mural so that your you can see most of the mural on your screen through the camera. Enjoy!