For questions that keep coming up in Discord
Dave has a FAQ video that covers most topics here, and some that haven’t been covered here yet.
What is sapiens?
Sapiens is a game where you guide a tribe of humans to create a civilization. Development started around December 2014 and is still underway, with a planned alpha release late 2019.
Dave describes the game in his YouTube video description.
In Sapiens, evolve your primitive hunter gatherers through thousands of years of technological advancement. Feed, protect and grow your tribe, build towns and industry, and advance through the ages in this first person civilization building god game for PC. Play with your friends in co-operative or competitive multiplayer, all on a procedurally generated planet larger than Earth. - Sapiens Devblog #26
What is the world like?
The world is 1.3x the size of earth.  It is modeled as a subdivided icosahedron (roughly a sphere).  Early on, the world will be very peaceful and primitive, but will become more industrial as you progress .
There will likely not be large natural disasters as Dave believes that the player should be at fault before they are punished. 
How far can you advance? Can you go to space?
Since the game is still in very early development, this is still up in the air. You will likely not be able to go to space in version 1.  The stock game will definitely go up to medieval times, and may reach the industrial age. [1, 2]
How much will it cost?
The price isn’t set in stone yet, but probably ~$20.
Around $20 probably. It just depends what ends up feeling right at the time, given what I end up with! - majicDave
Where can I get the game?
You can’t, yet. Sapiens is still in early development. There should be a closed alpha out late 2019 and a closed beta in 2020. If you want to be a part of the testing, join the Discord server to keep up with the development of the game.
You can put it on your wishlist on Steam today to be notified when it is released.
Can I be a beta/alpha tester?
Both alpha and beta testing will be closed.  If you want to participate, sign up on the forum and join the discord server. Dave will personally pick testers when the game is closer to a testable state.
When will testing start?
Not for a few months, it isn’t worthwhile yet. 
Sapiens is currently in the very early stages of development. Closed alpha testing is expected to begin late 2019, a closed beta early 2020, and a full release on Steam some time after that. - Sapiens homepage
What tools are being used to create the game? (Unity?)
Unity? Nope. Unreal engine? Nope. Sapien’s engine is completely custom, which provides much greater flexibility at the cost of more work. Why a custom engine?
Can I help with models/code/music/etc.?
Thank you for the offer, but no. Dave is a one man shop and plans to create everything himself. He might hire someone just before release to work on models , but there aren’t any openings right now. 
Do you have a Patreon? Can I donate?
With the final release, mods may be limited for security reasons, but during testing it will be wide open. 
What are the required computer specs?
I can’t really promise anything right now as far as minimum specs go, except that it will run well on a GTX 1060 or Radeon RX 580 or better, and will require a 64 bit OS, and a multi core CPU. - majicDave
Also see Dave’s post here
Clients will also require at least 4GB ram and 10GB storage space. 
These servers are going to need some grunt. I don’t know how much exactly yet, but in particular they will need plenty of RAM. (2GB or more per server instance is probably a reasonable guess) They only use one thread, so no need for lots of cores per server, but they could end up using a fair amount of CPU too. - majicDave
Will there be a Mac / Linux version?
You can learn more about the game through the following resources:
Very incomplete list, will be expanded as more questions come up in Discord that I expect to be asked again and again.