Abstract: A set of reconfigurable clip-on modules for mobile computing devices includes two or more modules and at least one of the modules has an input button or other control and at least one of the modules can communicate with the computing device without needing to be connected to it via a wire. The input button is mapped to a user input in a program, such as a game, which is running or displayed on the computing device to which the modules are clipped. In an embodiment, user inputs via the buttons or other controls on the clip-on modules are mapped to user inputs in a game running on the device, which may be a touch-screen device, and the mapping between user inputs via the buttons and user inputs in the game may change dependent upon the game being played, user preference, or other criteria.