IIRC, Markus Petersson, the creator of Minecraft, worked for a long time on Wurm Online, an MMO where you can kinda do what you're talking about - as a group or individual, you can level forests, dig down mountains, build roads, cities, etc. It's a slow and labor-intensive grind but it is a game where as a community you can change the whole game world's geography.

I saw it was on Steam the other day, I guess they tried to add some storyline to it.