This game is played in Google Maps.
You got a mysterious threat by the Rätsler and need to complete his tricky treasure hunt through Cologne.
Try to find the exact street view from a picture and look around for clues.
Follow the streets acording to the riddles and find the Rätslers' reviews scattered through the city.
Due to Google Maps not being a reliable game engine, some or more or all reviews might not work. Feel free to use the CheatSheet in case you can't continue.