This is a couple demos of the same Android prototype, one uses Qualcomm Vuforia and the other uses Metaio. I made the version with Vuforia about a year ago, but decided to update the graphics a bit, update all of the code to C# and I also wanted to move to Metaio to give me some more options for tracking (2D/3D Instant Tracking). So I'm posting up both versions for your perusal.
This prototype was really a proof of concept that a small playset with complex AI and interactions could be made in AR and be fun to play with. You can watch the activity in this construction site, or you can get involved and drive the truck yourself! I put in an additional camera to give you the truck perspective, and found this to be a really compelling way to interact with an AR environment, it reminded me a bit of the town creation portion of the game Dark Cloud. There is a lot of potential here to create some really cool interactive playsets.