Esri Canada’s Education and Research Group has created a 3D City Model Resources website to share free CityEngine rule packages and city model resources. The website acts as a rule repository where we have created some new rules, and collected existing rules that have been created by other CityEngine users. These Computer Generated Architecture (CGA) rules and rule packages (RPKs) are free to download and customize for your own use. You can use them within CityEngine, or apply them to 3D content in ArcGIS Pro.
Additionally, there is an interactive code viewer on the site that helps to explain rule creation, an online 3D model viewer, and demo videos to highlight how each rule works.
There are also resources to some great tutorials, and links to other relevant 3D City Model websites.