The received map concept comes from games like Metroid. You have a big map and must explore all over the vast world to open up the map. Another option is to receive a map which outlines other areas in the world for you. These maps can be attained from different means, In the Metroid Prime games you go to a map download station. In the exploring Castlevania games you can buy your maps. In the Legend of Zelda series there is a map for every dungeon which outlines all rooms. The interior of these maps is filled out as you proceed to your destination. It would be best for you to search every part of your map to make sure you aren't missing anything. And who knows, maybe exploring all of the interiors of a map will add to your percentage completion.