Age of Empires Online is a freemium multiplayer RTS game. While the game is free to download and play, access to additional empires and content requires the purchase of various expansions. Now the prices of said premium content have been cut in half, making it much easier to experience everything AOE Online has to offer (and get most of the game's Achievements). Additionally, the duration of Season Passes has been extended a full year to August 15, 2013 to make up for the new pricing structure.
Age of Empires Online New PDLC prices
Vanity Packs (Prices unchanged)
Limited Time Bundles
Not only are the new prices much more palatable, but the Pro Persia Launch Bundle sweetens the deal even more. Buy the bundle and the Greek Civilization and you'll get all non-vanity content for just $25. I've had my eye on Age of Empire Online for a while, and these deals are the motivation I needed to get started.