For an easier win against NPC characters, make a map using the map editor. Give 
yourself 99,999 of every recourse and your opponent about 20,000. Go to the options 
and disable the siege workshop and the trebuchet, then edit all the other options 
as desired and start the game. It will be a much easier game even under the hardest
difficulty setting because the risk of long ranged attacks and siege weapons that 
quickly destroy your buildings has been removed.