Hey there, future HEXimaniac.
HEX is currently in Closed Beta. You can download the client, but unless you are one of our Kickstarter Backers or have a Beta Invite code, you will not be able to play just yet.
You can sign up to be notified when we enter Open Beta and potentially get a Closed Beta key here.
If you have a Beta Invite code, you can create an account and enter it here.