The theme of the Ensemble Studios Heroes of the Ages Contest is, as the name suggests, heroes of the ages. To that end, scenarios submitted for the contest should be historically themed and should involve a hero (a larger-than-life historical figure) from the Age of Kings time period (roughly 400 to 1600).
Some examples of good choices for a scenario for the Ensemble Studios Heroes of the Ages Contest: Charlemagne's rise to power and efforts to build an empire, Harold Haardraade leading "Viking invasions" in England, Salah al-Din attempting to prevent Richard the Lion-Heart from taking Jerusalem during the Third Crusade.
Some examples of bad choices for a scenario for the Ensemble Studios Heroes of the Ages Contest: the historical figure Merlin and his epic fight against the dragons that used to thrive in medieval Britain, the one where the scenario is identical to any other scenario except for the fact that one unit is [insert random hero name here], 5,000 Longbowmen on one side of the map and 5,000 Paladins on the other, anything where the hero is "that dude from Gladiator".
All in all, the scenario should succeed in conveying a sense of the hero's story and his or her role in the historical situation selected.
That said, there are a lot of different styles of fan-created Age of Kings: The Conquerors scenarios; historical recreations, RPG-ish conversions, semi-cinematic sequences inspired by popular films, and so on - all providing ample proof that people can make scenarios which are vastly different from one another. However, what we're really looking for in the Ensemble Studios Heroes of the Ages Contest is: is it a fun scenario?
So, above all else, submitted scenarios should be fun.
Submissions should also consist of a single scenario only. Submitting campaigns (multiple scenarios) will result in disqualification of the entry.
All files needed to play the scenario must accompany the scenario submission. If you do anything complex, I suggest you include a "ReadMe" text document that describes what needs to be done as part of your submission. Any submissions that cannot be played after a reasonable attempt will be disqualified.
Submitted scenarios should take around 45 minutes of actual clock time (not game time) to play at the default (1.5) game speed.
Submitted scenarios should be playable at all difficulty levels available in Age of Kings: The Conquerors.
Submitted scenarios should include full text for instructions, hints, victory messages, defeat messages, etc.
Submissions must be done entirely with Age of Kings: The Conquerors. Scenarios using "mod packs" are not permitted and will be disqualified.
Submissions must be playable from start to finish without requiring the use of any cheat codes. Any scenario requiring the use of cheat codes to play will be disqualified.