Stronghold games are rts games.They are set in the Medieval and crusade wars time(Not including Stronghold Legends).In Stronghold you fight against a realy good AI(Well it depends who is your opponent.If you fight The Rat who is a weakling or if you fight The Wolf who is the final boss in the first Stronghold.)
A gameplay video:
http://www.youtube.com/watch?v=A6Uz7OMQ5JQ
Characther description:
http://stronghold.heavengames.com/sc/gameinfo/ai/
Stronghold 1 review:
http://www.youtube.com/watch?v=gVE8QXj5hrw