An open beta for Hearthstone which had been planned for December will now launch in early 2014, Blizzard has announced.
Regarding the current closed beta phase, production director Jason Chayes wrote: "We've been making great progress on improving server stability, but there are still a few things that have come up that we want to fix before we leave the closed beta phase.
"With all of that said, we believe the right thing to do for the game is to not rush it out into open beta, but to instead hold onto it a little longer to make sure it's ready for wider testing."
He added: "At BlizzCon, we mentioned that we hoped to get the game into a state where it's ready for open beta this month, but we're just not quite there yet. The development team has been working hard to get this out before the end of the year, but our highest priority is that Hearthstone has an awesome launch when all gates are lifted and everyone can download it and play at the same time.
"We're close to the open beta - very close. And to enter this final part of our beta phase, we need your help. Keep trying out new decks, reporting bugs, and giving your feedback on our forums. That's the best way you can help the team get Hearthstone into everyone's hands as soon as possible."
It sounds like the open beta may be ready at some point in January.