I lack any artistic talent so I am just throwing this idea out there.
What does everyone think of a total conversion mod to make the game like you are playing as a knight in a kings army? There could be 2 warring castles with small outlying villages that would trade openly. There could be vast armies of knights and archers and pikemen. Think of first-person "Medieval Total War" RPG game.
There could be triggered massive NPC battles of evenly matched sides so the radiant AI (scripted or not) and your actions (do you lead a flanking manuever around the right or try to split up the center?) will determine the outcome of the fight.
You could choose to help either one king or both or a mercenary side army.
Lots of possibilities. (a betrayer in a castle? assassinate a prince? fight in a royal tournament?)
Aspire to be great!
or
Rule the weak!
Depending on how easy the Construction Set/kit thing is to work with I might attempt this myself but as I stated I have mediocre drawing skills at best. A mod team would be ideal for this conversion.