I like the retro graphics. The new spacefish things keep appearing in awkward places though... maybe they should always come in from the sides, or fade in. And, it would be nice if it took a while after shooting them for them to reappear.

After playing a while, I got an IllegalStateException (Actor hasn't yet been inserted into the world). It seems you were calling "getX()" on an actor that wasn't in the world, from Building.drawProgressBar() (line 251)

I think those are gold deposits, Delmar. It seems like you attack them to get gold. Then you can build more units by first selecting your castle... this game is really coming along!

This is indeed quite impressive! I think turning (and possibly movement) could be a bit faster; you could then consider adding a small "skid" as in many 3D games (i.e. pressing forward accelerates, and you decelerate quickly after releasing the key but not immediately).