Tasks! And troops!
Although we have the achievements for gamecentre I think new takes would keep people more interested.
For these tasks, just like any other task you should get rewards and there should be different levels for these tasks which you will get a much bigger prize!
Tasks could be -
Upgrade every resource slot to level 5
- 10000 each resource and 1000 prestige
upgrade every resource slot to level 10
- 20000 each resource 2000 prestige
Then have level 15 and 20
Could also have ones like own 2 level 9 oasis , 5 then 10.
Also more troops!!! Like archers on horses! Pikemen etc
And have more techs which make the troops stronger. Like could have catapult tech which makes fire catapults.