The Curious Map is a special item that appears in the extra room of the Hall of Champions in the Sony, Xbox One and PC Versions of Shovel Knight. It's a slightly different item in the Sony version on the one hand and the Xbox One/PC version on the other hand, but it triggers an exclusive sidequest in both cases. A hint about the existence of this map can be heard from an NPC found exclusively in the Shortcut? area in both versions.
Sony Version[]
"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 makes Kratos appear on the map screen as a roaming encounter.
Xbox One/PC Version[]
"A map with a weird symbol... and there are some extra markings here!" - Xbox One/PC description
The Xbox One and PC Curious map has the Battletoads symbol on it. Acquiring it unlocks the Mysterious Area.