Hearthstone is Blizzard's first foray into strategy card games, a genre dominated mainly by Magic: The Gathering.
For those unfamiliar, the aim of these games is to reduce your enemy's health points to zero before it does it to you.
The enemy can be computer-controlled or another matched player over the Internet.
But instead of weapons, your tools are a well-formed deck of cards, which consists of creatures and spells.
Each card has a casting cost - also known as mana cost - so you need to build up your mana pool before you can play the desired card, which means a battle can take place over a dozen rounds of card- tossing.
In Hearthstone, you play as one of the nine heroes from the World Of Warcraft (WOW) game, including popular characters, such as the human mage Jaina Proudmoore and Thrall, leader of the Orcs. Each hero corresponds to one of the nine primary classes in WOW, which makes Thrall a shaman, Zuldan a warlock and Rexxar a hunter.
These heroes are not just for show. Each has unique powers, which can turn the tide in a hard-fought battle. The mage, for instance, can shoot a firebolt that deals one point of damage to minions or your opponent's hero at every turn, while the paladin can summon a weak minion to the battlefield every turn.
While you can earn hundreds of new cards as you play, you will have to pick only 30 powerful cards per deck. The cards are split into two types, with a series that can be used by any hero.
The other type are cards unique to each hero. These cards take after the skills of the heroes in WOW. Flamestrike, Fireball and Frost Shock, for instance, are class-cards that only Jaina the Mage can employ. Hunter fans will immediately recognise Hunter's Mark, Explosive Trap and Arcace Shot.
To make things simple, the game does not require you to add in cards which generate mana. You start with one mana on your first turn and then your maximum pool increases by another mana every turn, so that by the 10th turn, you will have the maximum mana pool of 10. Mana also replenishes automatically in each round, so by the 10th round, players will always have 10 mana to use in subsequent rounds.