Hearthstone, the WoW-themed online card game, opens to all

Pull up a chair! World of Warcraft maker Blizzard has opened up the beta version of its unfeasibly addictive online card game Hearthstone -- and it's well worth a try.

The beta opened up in North America last night, and will be opening here in Europe "in the next few days", Blizz promises. When it does, you can download the game for free here.

"Please be aware that if smoke starts curling out of our servers due to unexpectedly high demand for Hearthstone," Blizzard warns, "we may have to temporarily disable Open Beta account activations until we're ready to take on more players."

Lucky enough to get into the closed beta, I've been playing nothing but Hearthstone for the last few months. It's a genuine delight, full of charm and wit and tension.

You play against other players online -- there's a very quick matching system that pits you against players of roughly the same skill. You choose from nine classes that will be familiar to anyone who's played World of Warcraft, although it's very easy to learn. They each have their own special cards, which are a mix of powers and minions, and which you can supplement with neutral monsters.

You play across a virtual board, of which there are four, all with their own little interactive quirks. You draw cards from a deck, and take it in turns to play them. The goal is to knock your enemy down to zero health, and prevent them doing the same, by cleverly combo-ing your cards. Most of the monsters and powers are from WoW, and when you've finished your turn, the peon from Warcraft II says, "Job's done!" Like I said: delightful.

There are three play modes -- practice, where you play against the computer to unlock new characters; play, where you build a deck and test it against your devious peers, including your Battlenet friends; and Arena, where you build a deck from random cards, and earn prizes the more games you win with it.

Show me the money

Like all card games, Blizzard makes its money on you buying packs of cards. Two packs will set you back £2, seven packs £7, 15 packs £14 and 40 packs £35. You don't know what's going to be in them -- there's a lovely opening tool that's somehow really exciting every time -- so you'll get duplicates. Arena costs £1.50 to enter.

It never feels mean, and it's really not pay-to-win, unlike some free-to-play games. There's loads of ways to earn in-game currency, and the free cards are just as powerful as more exotic legendaries. Every day you're given a quest, such as 'win two games with Hunter or Mage' or 'destroy 40 minions', which encourage you to play as different characters. I've found I've earned enough for a new pack of virtual cards every couple of days, with little bonuses popping up every now and then for completing hidden achievements.

Including a couple of Arena entries, I've spent £10 of my own cash on the game. I think that's stonking value for the fun I've had. If you want to get up to speed before the beta opens here in Blighty, I recommend watching TotalBiscuit's Lord of the Arena series -- he's very funny and gives real tactical insight.

You can play on pretty much any old PC or Mac -- it doesn't need a graphics card -- and it's coming to Android and iOS later in the year (Blizzard is already suing a Chinese Android knockoff, GameSpot reports). I think it'll be perfectly suited to tablets. It'll feel so much more like a real card game to fling spells and minions by hand rather than mouse.

Here's Blizzard's primer video:

Have you been waiting to get in on the action? Have you played the closed beta? Do you think this is a good implementation of the free-to-play system, or should it be more generous? Take to the battlefield that is our comments section, or build a deck on our free-to-play Facebook page.