Urban transformation is key to achieving sustainable cities: from green facades to mitigation of rainwater sink, to solar potential, onto densification as a structural measure, we have many options available on how to achieve this. The actual implementation of such measures is, however, left in the hands of investors ‒ private or public ‒ the latter in the way of subsidies. Wouldn't it be of great advantage to know what the real outlook of such a transformation would be, in the sense of possible scenarios that are devised by the public (rather than a private and/or municipal body)? And applied over a city as a whole, without the hinderance of what is “public” or “private” in regards to ownership. This is the scope of our paper. We use publicly available data on cityscapes to get the current state, which is then transferred into a cellular automata representation on which rules act. These rules are specified via a web interface, so that everyone can propose possible ways of developing that landscape. Acting on these rules, a cellular rule engine develops the city into its green (sustainable) counterpart; the result is a projection of a city in the coming years, with the implied benefit of being able to talk on a much higher level than having to deal with every measure that individual players do at their own level. Our approach has the ability to play through different scenarios of different actors at a relatively early stage, in order to be able to judge their merits and contributions for achieving sustainable development of a city. We also democratize the “city-making” ability and bring its dynamics from the interplay between different private or public (municipal) stakeholders into the public arena, where many concerns and requirements actually originate.