Their "Sunny Sale" solution was brilliant! The company placed 3D QR codes across the city which could only be scanned between 12pm and 1 pm each day, when the sunlight cast the shadows correctly to complete the QR code. Once the code was scanned, customers would be rewarded with special offers that could be used in the store or online. Wow! If you want to know more specifics on QR codes work, see my previous post on QR codes.
Seriously, what an amazing idea! Check out the video below.