  As mobile crowdsensing techniques are steering many smart-city applications,
an incentive scheme that motivates the crowd to actively participate becomes a
key to the success of such city-scale applications. This paper presents a
crowdsensing WiFi advisory system called WiFiScout, which helps smartphone
users to find good quality WiFi hotspots. The quality information is defined in
terms of user experience and hence the system requires users to contribute
information of their experience with WiFi hotspots. To motivate people to
contribute such information, we design and implement a gamification-based
incentive scheme in WiFiScout. It allows a user to "conquer WiFi territories"
by becoming the top contributor for WiFi hotspots at different locations. The
contribution is based on the diversity and amount of data a user submits, for
which he will be rewarded accordingly. WiFiScout has been implemented on
Android and it facilitates the collection of city-wide WiFi advisory
information provided by real users according to their actual experience.
