From Valve Developer Community
What is Alienbrain?
Alienbrain is a content versioning system, or CVS, designed specifically with games in mind.
How do I use Alienbrain?
- First of all, you have to install it. This is pretty easy. When it comes time to install plugins, make sure you select all the ones that you will be using. You will definitely need the Visual Studio plugin; the 3DS Max and Photoshop plugins will likely be needed, but then again, it depends on your mod.
- Blah blah blah, im a dirty tramp