You can build multiple starbases; which leads to one of my biggest gripes so far. They build pretty quickly and are tough to get rid of. Plus they aren't very expensive, relatively speaking. So far I've had good success with the somewhat cheesy tactic of dropping a starbase (with some support, of course) in to enemy held space. While they don't win in-and-of themselves, they are a royal pain and take far more than they cost to destroy. I haven't tried it, but one of them also moves within a single system. Seems like this tactic would work even better. Still, they are cool. All those lasers, missiles, and ships launching from them to crush their enemies. Kind of Death Star-ish, although they look more like a square Cylon basestar.
As far as Demigod goes, I did say that my comparison to Sacrifice wasn't quite accurate. Just in the control of the demigod. And I can't think of anything else to compare it with. Maybe a chess-Sacrifice-hybrid? You directly control a demigod, a 3rd person avatar (like Sacrifice here). He or she can be upgraded with items (boots of +15% speed, armor, etc.). You have to capture control points around the map by standing next to them; each one can do something different (add troop health, -15% conversion time, etc.). Some of them deploy troops. You can't directly control these troops; they just head for the nearest enemy and start whacking. You can help them considerably though. You can also capture gold mines that allow you to purchase upgrade for your troops, for your avatar, etc.