Just a few hours back, Microsoft sprung a surprise by announcing Age of Empires Online at Gamescon 2010. The game is developed by a studio called Robot Entertainment. It will be a free MMO for everyone who uses an authentic Windows Operating system and the Games for Windows platform. The new title also features co-op multiplayer questing, trading, and a leveling mechanic in addition to story-based gameplay. It also boost a new graphical style that represents something of a stylistic departure from past titles in the series. Additional information from Massively.com.
The screenshots and trailer actually reminded me of a web-browser MMO I played not long ago, Ikariam.