I got a few ideas for the sequel for when it comes.
1.Natives-natives that have special units that you can recruit and special technology to help you in a fight
2.Multiplayer-it would be cool to fight against another player,maybe even co-op or 2v2.
3.Mercenaries-Powerful units that you can recruit before each mission.
4.Some defendse towers to help you defend your stronghoulds without getting units
If i have any more ideas il comment again.I love this game and i cant wait for the sequel :)