The Curious Map is a special item that appears in the extra room of the Hall of Champions in both the Sony and Xbox One Versions of Shovel Knight. It's a slightly different item in each version and both trigger an exclusive sidequest.
Sony Version Edit
"A map with a strange symbol... perhaps it was lost by someone?" - Sony Version description
The Sony Curious map has an omega symbol on it. Acquiring it leads Kratos to appear on the map screen as a roaming encounter.
Xbox One Version Edit
"A map with a weird symbol... and there are some extra markings here! - Xbox One description