They released the first Alpha release (Alpha 1) this week. The game is pretty basic and a bit buggy right now (as is to be expected with an alpha) and there isn’t a way to save your progress yet. Nevertheless, it was fun to play around with it and get a feel for the game. It didn’t take long for my workers to lose interest in building their house, stop following my orders, and gather up in a big pile, though! Yay bugs! 😛
If you want to play Stonehearth yourself, you can visit their store to pre-order the game (September 2014 estimated release date) and get access to the alpha.