For me the steps were ...
0. Buy game via Steam
1. After fiddling with humies and elves, start the Orc campaign in Swamp
2. build a fair number of huts early on, build units, and go raiding a bit to level up units
3. Play the campaign missions until Honor to the Victor shows up
4. Having brought too large an army including siege stuff, enter mission (not taking all units)
Not sure if any of these steps are required.
PC: AMD PhenomII, Radeon HD 5670, Win7