Things I wanted to do someday:

• I wanted to separate the simulation from the user interface. This would allow other user interfaces to be put on top. (I've considered an isometric 3-D view like SimCity 2000, but with hexagons and a map with 256 altitude levels it's somewhat harder to implement and somewhat disorienting for the user.)
• I also wanted to separate various parts of the simulation so that I can remove one part, appropriate for BlobCity, and replace it with another part, appropriate for The Silver Kingdoms. This may let me develop two games simultaneously, sharing simulation code that deals with generic blobs, path-finding, and the environment (water, weather, terrain, etc.).
• Transport Tycoon has a nifty feature that lets you bring up a small map around a selected unit, so that you can watch it go around. Unlike other games that have this sort of feature, TT's window is fully functional and it's always kept in sync with the main window. I'd like to have something like this for multiple views. Multiple views are fairly close to working in theory but I never wrote code to actually manage multiple windows.
• The map is going to support overlayed objects, like vehicles and soldiers. You should be able to right-click on these to get a context sensitive menu. This will be done with the new Tool Objects. (The Selection tool lets you point to an object and find out about it, but I don't have any menu pop up.)