First, looks like a great game! I'm having a lot of fun with the demo. Some UI comments/questions:
1. Upgrading - How do you upgrade individual units? Perhaps add an Upgrade Button to the unit window that appears when you double click on a unit. And/or add a right click menu to the unit list on the left for units that can be upgraded. This menu would contain an Upgrade menu choice. I might have 3units that are eligible to be upgraded, but only have enough money or want to upgrade 1 or 2. I'd like to choose which ones to upgrade (e.g. front line units as opposed to back line sentries).
Also, I have one class 1 infantry that I can't seem to upgrade.
2. Orders List - Add an orders list to the unit window. The map shows a unit's orders, but it's not always clear when there is a lot of stuff on the map. I'd like to make sure that my infantry, for example, is going to disembark from a transport and then march to a resource and then march to a city.
3. Allow production, research, national sumary, unit, etc. windows to expand in the same way that the Tech tree window expands.
4. Add a city tab to the National Summary window, displaying various info, including current production order and next production order. Double click on the city name to display the city production window. I sometimes have trouble on the map clicking on a city with units in it. The unit window appears when I want the city window.
5. Add a "Killed" or "Destroyed" column to National Summary - Unit Tab to display enemy units destroyed. I'd like to know how many enemy destroyed vs. how many of my units have been destroyed.
6. How does combat work exactly? Sorry if I missed it in the manual.