Here are some ideas for improving the game :
1. Mode play : Add a Mode play for 2v2 and 3v3 battles , Diplomacy is a great idea but still you should play might mode or Glory , you can not win with your teammates.
2. Contests and events : Create monthly league or cup contests to inspire users to spend more time in the game
3. End game : Add an option with the title " Draw" so people could suggest a draw in the late game , and they gain split ranking according to their scores , this could improve staying a longer time in the games that you have a little hope of winning .
4.Technology tree Suggestion :
Here i was thinking about history and i told my self there were small nations that could stand against big invasions , but in this game if you have a small territory you will probably loose, defensive strategies must be improved , so i thought what could help small territories to defend better against big opponents and it came up in mind the technology that could solve this situation is a new tec i named it : " Boarder walls"
Boarder walls could be built in any fields like roads with a price , they don`t have a counter attack , but they have bar health like units and they could be destroyed , but they prevent invasion of high speed units like knights and cymanti mobs into your lands , so you can make better use of archers and catapults .
The second technology that i was dreaming of is a defensive building that could hit enemy units while they are in its sight so i named it "Tower"
Towers could attack like units once per turn and they also have a health bar and could be destroyed .
With the "Boarderwalls" and "Towers" defensive strategies would be alot more effective