Wecity is the app that certifies the CO2 of your daily trips.
Record your travels and classify them as sustainable (bike, foot, public transport) or unsustainable (car): the former allow you to rise in the ranking because you have saved the planet from harmful emissions; the latter are harmful because they produce polluting emissions and make you lose your position.
Companies, shops and public bodies can provide prizes and economic incentives, pay attention to the possible reward!