Answer by robertbu

If you are using Unity 4.0, you should be able to use SVN to share your project. With 4.0, Unity enabled metafile support (Project Settings/Editor/Version Control) for the free version. Previously it was only available on Pro. You will need an SVN server. We purchase space on a server for about $4 US a month. There are sites that will host your project for free if you make it public. Here is a reference page on SVN: [Using External Version Control Systems with Unity][1] Note you will still have problems sharing binary resources like scene files. One method that might work for the two of you is to setup an ownership file for the scene. Also make prefabs out of anything and everything. That way changes can be made to the prefabs without changing the scene(s) files(s). [1]: http://docs.unity3d.com/Documentation/Manual/ExternalVersionControlSystemSupport.html