Ah,Battle for Wesnoth.I’ve played the game for 5 years and i’m still a total n00b at it.

First idea:

Download the Gambits Empire Builder add-on(allows you to farm crops with peasants,build buildings such as blacksmith,courtyard for meeting other races etc,castles…

In the first round the first player to build a fortress which is enclosed by castle hexes,contains all buildings,and has 5 farmland tiles with peasants farming on them wins.In the second round the player must create the same kind of fortress at center of the map.Since buildings are treated like villages,the criteria for the creation of that kind of fortress is possessing all the buildings within the borders of the stronghold,having peasants on all the farmland crops,having mages on all the windmills(they aren’t treated as villages) and having your leader on the keep of the fortress.If there are multiple keeps,then it’s enough if he just stands on one.

In the third round the player must deconstruct the castles of his enemies using peasants.The last player standing with an intact castle wins.

I need to come up with a second idea though.