AI War on Co-Optimus.

From the post:

I checked out the demo last week and came away
surprised just how deep this game is.  The game isn't for the faint of
heart when it comes to strategy.  Thankfully there's a full tutorial
available to walk you through the game.  The cooperative mode feels very
robust, but you'll definitely want to use some sort of voice chat
software because there's so much stuff to communicate.

Head
over to Co-Optimus
for the full post.