I create new Google Cloud projects using the Resource Manager API. As far as I now, passing the project ID is required. At least it's not marked "optional" in the REST API and also it fails if I try to create a new project with just the name.
However, according to the Google Cloud Resource Manager docs, there are some restricted words that must not be used in the project ID:
Some words are restricted from use in project IDs. If you use restricted words in the project name, such as google or ssl, the generated project ID will not include these words. https://cloud.google.com/resource-manager/docs/creating-managing-projects
Now, this happened to be a few times, e.g. "demo" also seems to be a restricted word.
Does anybody know a list of restricted words?
There is no public list of forbidden words for usage as project-id, however, your Project Id must be compliant with the Google Cloud Platform Acceptable Use Policy and the Google Terms of Service. In general lines, you can't use brands like "Google" and "Amazon", words that can be interpreted as impersonation, "hard" or "bad words".