you cannot use mouse and keyboard to navigate the menus properly. you cannot apply graphics settings. mine is stuck in 640x490 even though my native res is 1920x1080. when plugging in an xbox 360 controller you can navigate but again cannot apply settings as the game thinks its an xbox one controller and the start and back buttons dont work…well done microsoft. cant even get your OWN hardware working or simple mouse and keyboard navigation. here is a my vid of the mouse and keyboard problem - YouTube
Hey OP, please make sure to report issues like this to the Halo Support site 