Most games I play (i like the trader games a lot) have an feature which is called an GoldSink. Basically its something you can built which costs a gigantic load of resources. When I say gigantic, i mean really gigantic. Think about 100.000s of logs/marble etc.
In this game I suggest to name it TEMPLE. I got an fairly detailed idea also.
So, how does it work. First you need to clear your island. As the new place to built your temple will be a small island at the coast of Wild Marry territory. This also prevents the lower levels from accidently wasting tons of resources. I think it need to be a small island, but thats close enough to be reachable by an explorer.
On that island we place a building (temple) which is in ruins, and protected by an Dark Evil Priest, which holds an White Priest into captivity. But sadly enough your explorer is able to reach it but he also tells you, that an army is way to big to get there. You need to built a bridge first. Lets start spending resouces guys
Okay, the bridge has to built first, but an normal bridge won't do. You need an L5 bridge.
My initial idea is to make the bridge fairly cheap.
L1 Bridge: 5.000 pinewood logs. L2 bridge: 4.000 pinewood planks. L3 Bridge 3.000 Hardwood logs. L4 Bridge 2.000 Hardwood planks. L5 Bridge 1.000 exotic logs.
Doesn't sound too hard isn't it?
Okay, then you need to defeat that nasty Dark Evil Priest. People smarter then me, will be able to come up with a nice little army.
Dark Evil Priest is defeated and you liberate the White Priest. Then the White Priest ask you to rebuilt his temple and he shows you the ten spots where you can place the resources for the rebuilt.
The temple will have 10 Levels. And each level will be harder to built. In the ruins off the temple you will find a place where you can create buffs. It works the same as an provision house, but the buffs are called temple buffs. If you want to make an pinewood buff you need to bring pinewood logs etc. Fairly simple. Each of the ten spots only accept an specific item and the White Priest keeps track for you how many you already have donated to that spot. You donate materials to the building spots by buffing ofcourse.
To give an example. An L1 Temple will need 5x 10.000 logs and 5x 10.000 stones. Each spot can ofcourse be seen by visitors of your island, and it would be cool if you could show off somewhere else (which can be seen without visiting your island) how many levels of temple you got, but i haven't figured out how that would be easy to do. As soon as the ten spots are ready the White Priest retrieves the resources and starts building the Temple. Which would take at least an day. The new temple will make your population grow faster (I suggest 15seconds off the 15.00mins) and he offers to make 12hours lasting buffs.
The White Priest then comes back and tells you that you can make the temple better by refilling the ten spots with new resources. But this time he doesn't want pinewood logs and stones but something else. Lets say 3x15.000 pinewood planks, 3x15.000 marble, 3x15.000 copper ore and 1x15.000 hardwood logs. Then when the deposits are ready, he removes it and start building up the temple again. And the settlers willl now come every 14:30mins
We could even introduce 15hours buff at an L5 temple and and 18hours buffs later on, but you get the point.
Why I am using buffs?
1. It might be even a good idea to allow those buffs to be casted on other buildings except the temple spots, but ofcourse it also means we don't get to use Gold Ore for rebuilding that temple. (Fish might be another item we don't want to use then).
2. You can help another player by casting your OWN buffs to his spots. It might be even a trade option.
I don't think that gold coins should be in any of the items he needs. But other items like titanium bars, wheels and other items should be okay. It will also make MAKING those items something more desireable.
About the buffs I think we should move away from the normal items used in the provision house. Lets make it from flour, brew and meat This would also increase trade in those items.
Please note that it should be VERY hard to reach Level 10 templs. But its something to work towards it and the ONLY benefit would be lowered base settlers time and some special buffs who only last longer.