Hi.
its a bit different as what I was thinking of, did not know it would be a grid style selection.
For this you can even make it without arrays.
You could for example set the game object name to A,B,..,.,-
then use 'Ui Get Selected Game Object' and set a event to Object Changed Event.
on change, Get Game Object Name and set to the variable to show on screen.
and loop back to the state with 'Ui Get Selected Game Object'