Just like with Microsoft Flight a while ago, Microsoft decided to cease the production of new content for the free-to-play Age of Empires Online. The reason is simple: money. Development of these updates is expensive and so we’ll get no more features and civilizations, apart from a “small amount of content” to be released soon.
But Age of Empires Online isn’t shutting down. The game will live on, continue with its events and hope that players will keep coming back for more. That “more” won’t be anything new, though.