Sparrow whistle points were earned by whistling to sensor devices attached to the facades of houses in the neighborhoods. 8 sparrows were distributed to neighborhood inhabitants that volunteered to hang them. The sparrows contained custom-made electronics and a sparrow-shaped casing. Every time a person whistled to one of the sparrows, the sparrow would light up in a different color combination and points would be scored for the neighborhood in which it was placed. The sparrows appeared as separate players in the leaderboards on which the players could see the game progress. Whistling to a sparrow therefore did not score points for the individual neighborhood inhabitant, but for the team as a whole.