After a demo at WWDC earlier this year, LEGO launched the LEGO AR Playgrounds app for iPhone and iPad. 

The app uses ARKit to put digital LEGO characters into real-world environments and to interact with physical LEGO sets. It is a great way to introduce AR. A kid playing with the LEGO app can select various physical characters such as Ninjago Dragon Hunters and then interact with pre-selected sets in augmented reality. The two sets currently available that work well with AR include the LEGO Ninjago Dieselnaut (70654) and the Lego Ninjago Dragon's Pit (70655). 

ARKit enables multiple users so two people can play using the same playground. Two players can team up to battle against Dragon Hunters and figure out their attacks and how to win.

"Children today are mastering the art of finding new moments and forms of play and LEGO Playgrounds will provide a 'live' opportunity to test and learn directly with them. It's truly a unique way to engage with them in a fun and experimental way and bring them close to our innovation process. Having this direct-link to users creates a win for everybody – sharing the latest play experiences is great fun for children and highly useful for our LEGO design and development teams who can take their feedback and use it to make launch experiences even better and more engaging."

You can play up to five levels without a physical set. You will just nee a flat surface to play on. The app is free to use and free of ads, marketing messages and in-app purchases. To use the AR features, you will need at least an iPhone 6s with the latest iOS version. More information is available at Lego.