A few Ideas
1) Transporting resources and soldiers to people in your alliance. This would be the same as transporting between your own cities.
2) Ally list for alliances. This would make it so other alliances that are allied with your alliance will be able to talk in your alliance chat and transport resources and soldiers to each other.
3) Main building produces money. Why just fortified points? I think your main building should produce money, like 100 per hour for level 1, 200 per hour for level 2 etc. This would make the game a lot better because you don't have to sell your resources to get money.
4) Customisable ranks within alliances. An alliance founder should be able to make their own ranks other than just Leader, Vice Leader and Member.
5) More benifits for alliances. For example using coins you can add to your alliance's advantages, for example +10% on wood resources income, costing 100 coins. All members would be able to contribute, and once 100 coins have been donated, all members in that alliance would gain +10% wood resource income.
6) Upgrading your troops. There should be an 'Upgrade' button next to the training button for your troops, where you can upgrade the health, attack, defence, range and speed of your troops using resources.
7) Ever hate having 30k of each resource and 1k of just one resource, causing you to have to wait longer to upgrade a building or train troops? A new building called a 'Resource Converter' which converts like 10 wood to one iron or something should be added so you can convert one resource to another. This would also add some new techs to upgrade in the Technology Center.
Thanks for reading!
Spacel