Haven and Hearth is a java based MMO in development. It's unique in that there are MANY different aspects that meet and merge into one game. Basically it's a farming-hunting-fishing-crafting-village building-survival-fully PvP game, quite a mouth full. The game is in what the devs describe as "playable alpha" so it's still under a lot of development, which is both good and bad. The client and some game aspects are unstable and there are a lot of imbalances, but on the other hand, the game gets updated and changed fairly often.
Watch their outdated trailer, it'll give you a better idea.
Everything in the game is player driven. There are no quests, no NPCs (outside of hostile animals) and no shops. Players start off in random spawns and need to find resources and learn skills to survive, and it's tough. You're expected to lose a few characters in the trial process of starting out before getting settled. After learning to feed your character and survive, the next step is to build shelter. Building a house and surrounding it with a palisade wall will keep out animals. Once you have a safe spot, you need to CLAIM the land around your house. This will make it so other players can't steal your things without learning the PvP skills and leaving traceable scents. Once all that is set up, you're ready to explore and find other players and make your mark on this digital world. Not all players are friendly however, so be careful.
All in all, this game is amazingly genius. I personally can't wait for it to blossom into a finished game. If you wanna check it out here's the link. Just don't get too attached to your creations, as they reset the maps for testing periodically.