[math-fun] Directions to a map without knowing the starting position

Hello everyone I am looking for the name and/or more information about a class of problems, which consist of providing directions to reach a specific point on a map, without knowing where one is starting from. If I remember well, it wasn't even clear whether such maps existed - but some non-trivial examples have been found. The paths were coloured red or blue and directions given "take the red path, take the blue path, etc." Searching for the suspected keywords sends me to Google Maps etc., so I turn to the wisdom and knowledge of math-fun! Thanks in advance Seb