In a developer blog, Hearthstone production director Jason Chaye stated, ”While we’re psyched to have wrapped up feature development, it doesn’t mean we’re done quite yet. Our overall focus has shifted onto fixing bugs and improving our infrastructure so that it can support a larger number of players. We’re making good progress, and while we definitely won’t fix every bug before releasing the beta, we do think it’s important to address any issues that would pull focus away from the core game experience. What that means is that we’re not days away from launching the beta, but we’re not months away either.”
He added, ”At the Hearthstone announcement we committed to going into beta testing before the summer was over, and the team has been pulling out all the stops to make that happen. Sometimes that has meant ditching meetings to fix a gnarly bug, and it’s often meant working long hours to get that additional layer of polish in. It’s a pretty intense time, and what keeps us going is that we’re just as excited as you guys about the release of the beta.”
As far as the selection process for the beta: ”One last point on the beta test: while we’re going to kick it off with a relatively small number of invites, we’re going to gradually roll in more and more players over time. If you don’t get in initially, don’t worry too much, as new players will be brought in frequently. In fact, everyone who’s interested in playing Hearthstone during the beta period will be able to get in when we transition to an open beta test a bit later in the testing cycle. All you’ll need to do is create a Battle.net account if you don’t already have one, and download the client, and you’ll be set to go! No invitation necessary!”
Blizzard first announced Hearthstone back in March 2013.