This is just a scenario where you must defeat Lord Sunday. It is based on the 'Keys to the Kingdom' book series. I don't play AOM: The Titans much so please excuse any mistakes in the scenario or errors. You start of with small amount of resource and have to try and capture Plenty Vaults which are located around the map, or just use the natural resources to fund your army. Then you can find and kill Lord Sunday and his servants (Noon, Dawn and Dusk).
Extract, drag or copy the file "Sunday's Realm(V2)" to
D:\Documents and Settings\"user (e.g. Void Dragon)"\My Documents\My Games\Age of Mythology\Scenario
C:\Program Files\Microsoft Games\scenario
I'm not sure which one though so try the other one if it doesn't work. Otherwise, notify me and I'll have a look exactly where it is meant to go, or perhaps ask one of the proffesional AOM players who are probably lurking around this site as well somewhere.
Cheers, Void Dragon