FunKey-OS is a Linux operating system distribution developed for use on the FunKey S. The default application launcher of FunKey-OS is RetroFE, though future support for Gmenu2X as an alternative launcher has been announced. As FunKey-OS is open source, the distribution and its source files are both publicly available for download on the FunKey Team's GitHub page.
The default RetroFE-based FunKey-OS launcher separates and displays games loaded onto the FunKey S based on emulated system. How these system game lists are displayed depends on the theme selected by the user, with Classic, Flat, FunKey, and TFT being the default options. Additional themes created by users can be added to the FunKey-OS to further increase the variety of themes. Each game listing includes that game's name in addition to a box art image, as long as that a box art image with a matching file name to the game ROM file is present. Depending on the selected theme, the size, density, and screen location of game titles and box art images can vary based on user preference.
When available, the alternative Gmenu2X launcher will be able to be swapped to from within the system settings, giving users the additional options for configuring their user interface and applications. It will also provide developers with further tools to develop custom games and applications for the FunKey S.