Guide will spawn at beginning of game.
Merchant will spawn once the player has obtained 50 silver. (50 silver coins)
Arms Dealer will spawn once the player has obtained a firearm. (You only need to get the gun, You dont need to fire it.)
Nurse will spawn once the player has extended his max health. You can extend your max health by finding/using a "Crystal Heart."
Demolitionist will spawn once the player has made/found "Dynamite" or a "Bomb". You don't have to use the either. It just has to be obtained.
There are 2 other NPC's. They aren't very nessesary. "Dryad" and "Old man" A.K.A Skeletron.
