These are the things I'm working on next. I may not get around to everything, and may post updates before this to fix bugs.

1. Improved saving and loading.  Basic city and resource structure is saved properly. Base connections don't always render properly when loading. Enemy/combat status and some building properties don't currently save properly. Also, the UI is really, really gross looking.
2. Shield Generator The effect and mechanics are almost ready, but I need to do a few more fixes before  implementing this. Shields will add a nice effect and give yet another reason to stockpile energy for emergencies. 
3. Economy Tweaks Right now, worker drones are assigned automatically. I would like to add a simple slider (or other UI element) that lets you control how many drones are used for mining or construction. This will enable players to slow down especially big or expensive projects so they don't stall out their economy. 
4. Visual Improvements Space traffic around residential areas, better effects for structure damage/destruction, new levels...

Of course, my first priority is fixing bugs. Thank you for your patience!