Arcen Games: "The AI War: Ancient Shadows beta kicked off this past week, and already we're seeing some great coverage coming in for the expansion. The latest update is out now, offering the first major content release on top of what was initially packed in.
As far as getting the expansion to work with a Steam copy of the base game, you only need to download the installer and point it to the AI War folder in your Steam directory. We've been fielding that question a good amount over the past few days, so thought I'd share that bit of info here. We haven't reached out to Valve yet in regards to bringing Ancient Shadows onto Steam, but plan on it when the expansion is closer to being feature complete."