There are occasions when the rink is all one color, with no surrounding one-color rim. Fusion can handle this as well, but needs a Color Sensor. This sensor is not part of the Fusion Base Kit, but is available for separate purchase from Modern Robotics. When the Color Sensor is used, you will need to know the “Utility Frequency” of the electricity supply in your country. In Tasmania this is 50 HZ, in the USA this is 60 Hz, and you can find the Utility Frequency used in your country by clicking here.
Note: Currently (July2018) only one Color sensor may be connected to the Fusion Controller at a time. My understanding is that this is a limitation of the current Fusion implementation of Blockly, not a limitation of the Color Sensor/Core Controller combination itself. Thus, this limitation of only using one Color Sensor at a time could change in a future implementation of Blockly.