Stone's shop should be more dynamic, in that she should be aware of the
equipment that Tux has, and tailor what she sells accordingly.


Tux walks in with a gun, Stone should have the appropriate ammo for it.


Tux has no shoes, Stone only sells "Shoes".
Tux has "Shoes", Stone sells "Shoes" and "Worker Shoes".
Tux has "Worker Shoes", Stone sells "Worker Shoes" and "Battle Shoes".
Tux has "Battle Shoes", Stone only sells "Battle Shoes"

Something similar can happen with armor, and helmets, etc.