Zaya Learning Labs is an elearning organization that created English Duniya, a mobile application that uses gamification to teach kids English:
"Every child can now learn English on a learning pathway made just for them. As your child explores English Duniya, they will watch videos and answer questions at their reading level.
Currently available in Hindi and English for grades 2-5. More Indian languages and grades are coming soon."
The child needs to clear each level before unlocking the next one. The child gets points for watching the video and attempting practice questions.
The developers of English Duniya recently gave a talk about their reasons for choosing to develop their application using Angular, Ionic and Phaser, which you can find on their web site.