What determines the right user experience for a platform/device?
- User posture: Stationary, Lean back, on-the-go, shared
- Input capabilities: pointer/keyboard, LRUD/OSK, Gesture/OSK
- Navigation style: controls & windows, panes
- Display capabilities: Hi-Res, near, far away, small, medium, large
Design principles (fundamental, universal ideas that underpin good design) stay the same but the application of principles varies across input, posture, navigation, and display.
Design for mobile first when thinking about multiple platforms as it holds the most constraints. This helps you focus.