While some of the new gaming phones have hardware controls - either on board or as accessories - most handsets out there rely on touch and motion. Those are fine for casual games, but Microsoft believes it can interest serious players with Xbox-like controllers. This is just a research project for now, but the vision of the team is for Switch-like flexibility. They controllers themselves - analog sticks plus a D-pad or a handful of buttons on each side - are relatively small and they attach to the side of the device (be it phone or tablet). Additional slide-in grips can be used for...
Source: https://www.gsmarena.com/microsoft_experiments_with_modular_controllers_for_mobile_devices-news-33961.php
