Radius color is customizable. By default it is grey. To change radius color open or create a task and go to “Additional settings” tab. Pin radius color is also used in Clue game’s task list. To hide the radius (area), you can just set area color transparent.
Radius is an area where task actually activates, it is a circle around the pin icon. Default radius is 10 meters but you can change it, we do not recommend to make it smaller because of GPS inaccuracy which will make it hard to activate the task. Radius can be changed while creating game on “Locations” tab (for general tasks) or while creating/editing task on “Location” tab (for location-specific tasks).