How much of the game is there left to be made?

[SimplyMole]

So my friend and I are playing on the patch 0.5.1, and where wondering is there going to be only one more main quest and that's it? We would like to play more. A lot more. The game is just too good to end so quickly. I do understand that it's still not finished, just wanted to know if there's going to be a lot more to it?

I haven't had this much fun playing a new game in years. 

Thank you.

[Ethics Gradient]

You can check out the Grounded Feature Board to get an idea of where the game is going.  

There's no official "the game is X percent done" figure, but there are still two major biomes to go, and a lot of missing plot to start tying it all together.