The GUI shows the board, tiles with a round ring are the areas which have a movable valuetoken (can thus place an available value token there).\
The tiny hexagons are cities, purple are the cities which can be claimed from the start.\
Click on a tile with movable value tokens to place a new value. Change how you value each kind of resource relative to the others and the number on the cities will update and show what "score" they have.\
