Sure thing! Decentraland as a project has parts of it that are complete and operational (like the MANA tokens operating on the Ethereum blockchain (source code for those contracts over here), and the Marketplace (source code over here).
However, other parts are still in development, and my comments/ideas are about the next phase of the project, which is creating a browser/viewer for multi-user interaction. Developers wanting to create content currently can follow Decentraland's SDK Documentation, which uses their CLI tool to create and build a local representation of the 3D world.
My comments are mainly in response to the Documentation/SDK directly, which shows the Decentraland team's current direction for putting restrictions/structure into the 3D world the CLI tool creates. For the sections I talk about:
- Road placement/appearance: visible in the overview maps in the Marketplace
- Building height: current height restrictions defined in the SDK
- Parcel dimensions: current 10x10 meter size is listed in the SDK's FAQs