The placement with the mouse would be ok, i thougth with thqat more as something like it was in an earlyer version were a key was in every menue that is open for something else and it was always the letter that is the first that the name has but the others not. Arrow keys would work in theorie with hexes but it would mean that you cant use up or down and ned du use up and left or up and right together and the same with down. It would work but i think it is with the mouse realy easier to place something in the game.