ThemeChanger.exe is a miscellaneous executable gained in Hacknet used to change your display design and colour without requiring an x-server.sys switch and reboot. It is first gained after the first few CSEC missions where you are told that a new program has been added to the CSEC Asset Server. The available themes in the game are accessed by being copied from other computer nodes in the game. It can be run by typing 'ThemeChanger' into the command