Using Zope 2.3.0b2, I've found that if I create a ZClass with "Include standard Zope persistent object base classes" enabled, I can instantiate the ZClass right away. If I don't have it enabled, I can still create the ZClass, but instantiating it gives me the following error: Zope has encountered an error while publishing this resource. Error Type: AttributeError Error Value: _setId I understand the difference between checking and not checking the option, but unfortunately, I'm just starting with Zope in general so this error is not obvious to me. Is this correct behaviour? Also, I'm interested in whether Zope can be used to write web games, e.g. along the lines of Blacknova.net's use of PHP. Are there any examples of Zope games on the web? Thanks. Gerald.