Hey lyndontroy sorry for the late response, I think this should work sounds like a cool idea. You should just be able to setup a CGF with a type of 'Gravitational Attraction' and sent the force to positive, you will need to use the fix above for the alignment, and yes it does consider mass when using the 'Gravitational Attraction'. I dont have a manual, but I do have the video tutorials under 'Tools->CGF3->Tutorial Videos', I'm also working on a web wiki here later in the future. Hope this helps let me know if you get it working. Cheers!