Fallern Earth.
 

Yep that little known MMO is now free to play on steam with the pay to play "upgrades" of course but even without them for a cross between the fallout games and wow with semi bad graphics its actually a pretty decent game.

Its got plenty to do and explore a decent community and best of all it has a fps style combat system so no putting a rock on F1 and sitting back.

IMO well worth the download.