Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Can you recognise this mobile game?
It's from a YouTube review video about OnePlus 5:
OnePlus 5 Review: Still the best value? - YouTube
The game is Clash Royale by Supercell.
It is available for both Android and iOS.
Required, but never shown