making a free to play version for steam, which is very small download size and just a skirmish against an AI. Make it very convenient to try and let people get a taste for it. This RTS is so fun but most people will never give it a chance. I think this would work really well at getting new players in.
If you enjoy a skirmish with 1 civilization and until easy AI is not a challenge, chances are you will want to purchase the game and explore other civs and harder difficulty. If you don’t enjoy, no harm done and nothing lost for Microsoft.
This game get amazing support and its such a shame more people aren’t involved and enjoying.
William Wallace campaign being free is good for new comers. This is the tutorial to help new players learn how to play. Besides, I will suggest allow skirmishing with Byzantines/Mongols for free. They have very wide tech tree and give players a taste of different strategies.
I would suggest to have Celts as the demo civ, since we are including William Wallace campaign. However I see nothing wrong with Joan of Arc/Franks too.