Move with WASD. Weapons fire on their own. Tab, or the map in the corner, opens the chart: lit stone is where you have walked, ? marks are rumors, and the diamond is only a rough bearing on a hidden arm. A keeper guards it, themed to the weapon, and will not stray. Run far enough and they heal and return. They are nearly as hard as Robert the Jacked.
Maps
Locker
Locked pieces show how to earn them. Equipped weapons and armor come with you. Hidden map arms, once found, are always on.