Modular Gaming
Modular Gaming Open Source Persistent Browser Based Game Framework
...If you wanted just a forum you could enable only the core, user and forum modules.
We are building our framework using Kohana which is an open source, object oriented (H)MVC web framework built using PHP5 by a team of volunteers that aims to be swift, secure, and small. We are using Kohana 3.3
You can view a demo at http://demo.modulargaming.com
If you have any questions, bugs or feature requests feel free to post them on the issue tracker at GitHub. https://www.github.com/modulargaming/modulargaming
Licensed under a BSD license. ...