What about a map where the goal is to produce a maximum of goods? The challenge would be to produce as many goods as possible in a given time - 5 or 10 game years (More?) - with some events to prevent it from being too easy.
If the game is set on 10 years for example, make a scenario that runs 11 years, and by december of the tenth year, make a save and send it to show what has been produced by that date...
It would be related to some or all of the available goods, and rated with a rate scale for each of the goods...
Also, it could be done on one map with different challenges: for example, one challenge would be to fulfill a goal with different types of goods, and another one would be to fulfill the goal with only one of the available good.
It would be some economic challenge instead of fighting or surviving; but could be mixed with some bandit attacks if it's an economic map, or with enemy attacks if based on an invasion map.
The goal, anyway, would be to produce a maximum of things in a limited time... It's kinda contest, yep, but with no goal to reach besides to produce as many of a good as possible in a limited time.
There would even be several ways of playing it:
To produce as much gold as possible.
To produce as many weapons as possible.
To produce as much food as possible.
To produce one given good as much as possible.
(This one could be extended to all types of goods...*grin*)
And, of course:
Basic total run for all available goods.
Playability could be improved with a few small invasions on an invasion map, and with some bad or good events as well, except fire to personal my point of view... Of course, plagues, bandits and wolves would be a must...
The idea is to try to make it with one of the goals, with several or even with all. It gives the opportunity (and necessity) to play the map different times (Different ways?) in order to achieve all goals... Now, what size map should it be? A large one I guess to increase difficulty due to the location of the ressources.
The challenge would be to produce a map that offers many ressources to exploit, not all displayed together... (Like iron spread a bit all over the map and not located in quantity in one place for example) I thought of a "place your keep" way of playing, it might as well be with an already placed keep... It depends how the ressources are placed. There is a rating per good -when you finish a map with economic goals- that could be applied to the results if the goal is to produce several types of goods.
It would be good to start with just a limited amount of wood and food, and with no gold too.
Regarding the invasions, if invasion map, it would need to be not so strong ones, with the idea of bothering more than killing your lord. If the castle is closed, monks, spearmen or macemen make wonderful teasers... They shall kindly destroy some of the things you built until they are stopped.
Scripting would be a great challenge as well, a good balance would be needed to bother the gameplay only where it hurts.