Platform UI guidelines are aimed at making application more approachable for the users. When it makes sense to depart from platform conventions when developing cross platform application or service?
- App Stories Episode 12: The State of Non-Native Apps
- All apps using Windows 95 standard controls looked the same. History repeats itself with Android (How are all the Material Design apps so similar? - Quora)
- Games newer follow UI conventions of the platform
- Experience with an application on different platform vs. experience with the platform itself
- Take a look at examples in How to design a mobile app across OS platforms?