These effects are all intended to create an immersive story for players to dive into or avoid without much fuss either way. Blizzard has also taken every opportunity to impart story through its classes' personalities, giving them each a voice and a character which changes how NPCs respond to them. The same guard who chastises Wizard players as being boozed-up glory-hogs, and regards Witch Doctors as bizarre curiosities, will act sycophantically to Barbarians - a satisfying experience if you have played as the former two classes first.
In Diablo, each class has ultimately never been anything more than your vehicle to loot, and this has been furthered by the introduction of runes - items that drop in the world and alter the effect and appearance of skills and abilities. Inspired by the original skill system used in Diablo, whereby characters would learn new skills from book drops throughout the game, runes, according to Wilson, will allow gamers the ability to customise their characters to greater depths.
"In Diablo II, you could have a Barbarian and I could have a Barbarian and they would look different based on the skills that we choose," he said. "We wanted to enhance that even more, so that if you had a whirlwind Barbarian and I had a whirlwind Barbarian they actually still look different because you chose to do a particular skill, versus a skill that I did."
Runes are what I can only assume to be Blizzard's attempt to drive the final nail into the coffin of your social life by creating an eternally repayable game. Apply the multi-strike rune to the Wizard's electrocute ability, and you'll create chain lightning; or combine the skill with a lethality rune and it causes creatures to blow up, damaging surrounding enemies. The runes are entirely interchangeable and can drastically alter the utility of a skill, granting each different combination a different style of gameplay.
So far only three classes have been shown, the Barbarian, the Witch Doctor and the Wizard. Each one of these classes carries a distinct personality: the Barbarian is clearly represented as the 'noble savage' - he talks softly, but carries a big stick. As the main tanking class, the Barbarian comes with a host of smashing attacks that devastate a single opponent or send waves of minions flying back. The class also features a range of buffs that become accessible when the character reaches a certain level of rage.
The Witch Doctor, the first new character introduced, is an iteration of the Necromancer from Diablo II. Although he controls zombies, plagued toads and summons flurries of firebats, the character is far more spiritualistic and concerned about doing good than his appearance would suggest. The zombie dogs raised by the Witchdoctor can be further enhanced when other abilities are on them. For example: fire abilities catch the dogs alight, causing damage to all mobs and scenery.
The Wizard is by far the most developed class in terms of character and skills. She is presented as headstrong, arrogant and individualistic. The Wizard represents the ideal 'glass cannon', inflicting insane amounts of damage, but being relatively weak herself. One of the highlights of playing the character is in using the 'disintegrate' skill down a packed corridor and watching as the enemy explodes in a vain attempt to reach you - it's incredibly violent, easy, satisfying and can instantly cause you to bellow menacing laughter.