Games are popular as ever. Professionals from every field are trying to build their serious games, combining engaging playability with simulation and learning outcomes. Urban planning is no exception. However, materializing these games is no easy task. We propose a serious game development process to combine modern board game mechanisms with realistic urban maps, profiting from the simplicity, flexibility, and collaboration dynamics analogue games provide. For this, we tested two collaborative games with architecture students. Although different, the games have similar core mechanical and economic systems, modelling urban zones with hexagons and squares. The experience revealed some pitfalls to avoid in game-based planning practice and helped to define a development process for serious games for urban planning.