Per in-game tooltips, I can see that one may press
B to open the Attack or Ranged Attack menus, respectively (as well as to do nearly everything in-game without the mouse).
However, is it possible to actually attack without the mouse? Can I use only my keyboard to attack? I have a bit of repetitive strain injury on my right hand, so I'd like to go full-keyboard if at all possible.
Solutions not involving 3rd-party software highly preferred.