<snip> AI War: Zinth Artifacts. That, more than anything else, really captures the spirit and nature of the expansion, I think. Even better than Zinth Remnants.
Given the very short backstory, I don't see how, would you mind elaborating? Right now, they look just like traders rather than the Ancients from Stargate.
Unless I missed something.
Well, the idea is that the Zinth are much more advanced than the humans or the AI (the AIs only having a bit more technology than the humans based on what they have developed in the last few years of the war). So, the Zinth are clearly and older and wiser race, but it's not clear exactly how old they are. The Zinth that have been previously encountered were simply traders, but given the nature of the weaponry and technology they have traded, there is clearly much more to their civilization than the humans really know. The fact that the Zinth Starship is insignificant enough to be traded away to humans suggests that it is not a threat to the Zinth themselves... that their real weaponry is vastly more advanced.
One major new class of ship that will be in this expansion is Golems. These are gigantic, or otherwise strong and imposing, ships that will be scattered around the galaxy in a broken state. Players can capture them by capturing the planet, and then repair them (at large cost), to turn them into a huge war machine. If that war machine is ever lost, it is gone forever, but as long as it is carefully guarded and periodically repaired, the Golems will be the most fearsome ships the players have access to. Most likely they will come with some other negatives, too, that make them expensive to maintain and use (thus keeping them within the realm of balance), but that's the general idea. These are basically artifacts from the Zinth civilization, picked up now by the players.
Beyond that, a lot of the technologies that are going to be in the expansion are Zinth-based, arising from the resumed trade relations between the Zinth and the humans/AI. Plus, the Zinth themselves will be a minor force in the galaxy, and they will be able to turn more major (in favor of the AI or the humans) depending on certain factors. Some of that is still TBD on actual mechanics, but that's the idea.