Mine craft like elements,but is 1 world, Free to Play, still early in developement: Download
Can try currently though....looking for ppl to try it out with me....see if we can build a town!
Mythruna (myth + rune + a) is a game under development attempting to combine serious role playing elements with an endless, living, and completely modifiable randomly generated sandbox world. When completed, Mythruna will be a unique gaming experience.
(more explanation on Game Site)
mythruna.com