I can't believe I hadn't considered these forms of input properly. Until today They Are Everywhere was joypad / touch only. But the GUI responds nicer to keyboard and mouse input now and the game is playable with keyboard input. Not so sure about mouse only playing, that could end up messy with the limited directions I'm forcing on the player but I should really add it for completeness, 2 buttons and movement in 2 planes is the minimal input needed after all, negating pause functionality.
So, I have a more complete GUI and better input handling today. Not the most exciting news I'll admit but important nonetheless.