Collectible Card Games have had a fairly long run at this point, with the advent often considered the 1993 release of Magic: the Gathering. Where Magic has had better than two decades to develop a complex ruleset (almost 200 pages of legalese), Hearthstone is a fledgling game with a very limited selection of cards, and a very basic, easy-to-approach set of rules. This is both the greatest feature and biggest downfall of the game, as it opens up the target audience well beyond the reach of a rules-lawyer-friendly MTG, but simultaneously limits the sort of advanced interactions that keep players coming back to Magic for years on end.
Hearthstone is the epitome of casual. It's easily approachable. It's free to play. There are plenty of microtransactions. You can also sink hours and hours into it without realizing it, even though a match can take as few as five minutes. Most importantly, it's highly addictive. Whether you're drawn to the collection side of things, powering through Arena runs (which we'll touch on later) for the prize pack, or drawn to the competition available in Ranked play, if you've got a compulsive bone in your body, you'll have a hard time putting it down.
The core gameplay is uniquely simple. Each turn you draw a card and gain one Mana Crystal. You cast increasingly powerful spells and minions, which you use to try to whittle your opponent's life from 30 to 0 before they whittle yours down. There are nine classes, ported over from World of Warcraft, which makes it a really neat universe tie-in, and, in true Blizzard fashion, the essence of each class was captured to a tee with their unique cards and abilities. Each class has a "Hero Ability" which they can cast once per turn for two mana. These range from the Mage's "Fireblast," which deals one damage to any target, to the Priest's "Lesser Heal," which heals any target for two.
The beauty of Hearthstone's gameplay is its simplicity. There's no complex ruleset that you need to learn in order to understand what's going on. You just cast your spells and summon your minions. It's all the fun of a more complex CCG, distilled down to the most enjoyable components, with a heavy focus on creature combat, which is easily overpowered by the flexibility of spells in other games.
While the terms TCG (Trading Card Game) and CCG (Collectible Card Game) have been used largely interchangeably for a while now, the fact is that Hearthstone is truly a CCG. There is no way to trade cards or gold, so your collection is only ever yours. There is a crafting system in place, however, which allows you to destroy your unwanted cards in exchange for Dust, which can be used to create any card in the game. With a good portion of all Legendaries (the highest rarity) being largely worthless, it's good to have a way to trade in the junk cards for something that you'll actually use.
Once you make it through a very lengthy tutorial, you'll be able to play in basically three modes. Casual Play mode lets you play games with decks you build from your own collection with no penalty for losing. It's a great way to test out a new deck build, or just get your feet wet when it comes to a live match. Ranked Play is the same, except it pits you against tougher players, all vying to earn stars, which add up to ranks. You won't lose stars in the first few ranks, but once you get past rank 20 or so, you'll risk losing a star when you lose a game. On the flip side, winning three or more games in a row awards Win Streak bonus stars, helping you rank up even faster. There's not much more than bragging rights on the line for ranking up, but the launch introduced one minor incentive: novelty card backs.