A Tale In The Desert ( atitd.com ) is a subscription graphical MMO which has some limited properties in common with what you describe. It's cooperative, it's n

A Tale In The Desert ( atitd.com ) is a subscription graphical MMO which has some limited properties in common with what you describe. It's cooperative, it's not graphically sophisticated, and collaboratively climbing a (relatively shallow) tech tree is the main goal of the game.