BlizzCon 2009 Diablo 3 Official Preview
From Diablo Wiki
Blizzard offered a short Q&A with Jay Wilson, previewing what fans could expect to see of Diablo 3 at Blizzcon. The following is all quoted from their pre-show media coverage. 
BlizzCon 2009 Diablo 3 Preview
BlizzCon 2009 is right around the corner, featuring -- among many other things -- hands-on demos of Blizzard games in development, including Diablo III. In this Q&A, Diablo III Game Director Jay Wilson talks about what players can expect to see in this year's demo and what players should look out for when battling the hordes of the Burning Hells.
New Monster Behaviors
One of the ways that Diablo III improves upon the previous games is by providing more complex and challenging monster behaviors. Are there any monsters in the demo that showcase this?
Jay Wilson: When they're checking out the demo, players will see quite a few instances of monsters working together against the players, and that's one good example how we're making things more interesting and exciting this time around.
Sand Wasps, for example, shoot slow-moving projectiles at you from a distance. Their shots are easy to dodge and individual Wasps are easy kills, but in large groups they can quickly fill up the screen with their tiny bolts of hurt. If you're fighting against other, more powerful monsters, Sand Wasp swarms will force you to keep moving, giving the other monsters more time to do damage.
Then we have the Dune Dervish, which is much more powerful on its own. Dervishes are big, strong monsters who usually just float around the desert, but once they spot you they will start spinning really fast, causing a lot of damage to any players near them and reflecting all the players’ projectiles that head their way. A Dune Dervish breaks up the regular play rhythm by forcing you to back off for a moment until he's done flailing around, at which point he’s a lot less dangerous.
Having a few monsters that shake up the rhythm like that every once in a while is important because it makes playing through large areas or dungeons a lot more interesting and dynamic.
Diablo III will present players with dynamic, interactive environments and set pieces such as crumbling walls or collapsing bridges. What kind of cool stuff should players look out for in the BlizzCon demo?
Jay Wilson: There are about a dozen randomized events that players can stumble upon in the demo. We like to do some foreshadowing, dropping some clues about what's waiting for players a little ahead of time, but with randomized environments that's not always possible. We do have a lot of cool scripted sequences in the demo though. To give you an example, in one of these encounters you'll find a man in the desert who's trying to warn you of Dune Threshers in the area...mere moments before one of the creatures bursts through the sand and devours him.
There is also another fun sequence where you're in this underground dungeon that's starting to collapse, so you have to make your way out in time -- but there is a lot of treasure down there, so you have to make a call whether you want to risk getting crushed for some sweet loot or play it safe and pass on some potentially awesome treasure.
In terms of quests, there is a main quest and 12 to 18 side quests in this demo, which is a lot. There's also a storyline in there that ties into a piece of lore you can find on the Diablo III website, "Encounter with Burrowing Death." I think players who read the piece will get a kick out of finding this story in the demo.
Playing Solo or MP
Do players have the choice of either playing solo or with others in the demo? How will the single-player and multiplayer experience differ in the Diablo III demo?
Jay Wilson: Players will have the choice between going it alone or teaming up with others. Single-player gives you the chance to experience the game at your own pace…to stop and smell the blood, so to speak. When players play together with friends, most tend to proceed at a much brisker pace. There are also obviously some balancing differences. In multiplayer, monsters have more health, drop fewer health globes, and hit a little harder. And, of course, we drop loot per player, so if you see some great gear on the ground, it’s yours. You don’t have to worry about stealing it from your teammates.
Things can get frantic in multiplayer, but I hope players will see in the demo that we're aiming for an experience that feels truly cooperative. We don't want players to disperse and go off on their own. We want them to stick together and have each other's backs. The demo now includes our current version of the in-game map, which has hint arrows that should make it easy for people to find each other.
Another thing to note is how we’re handling death in multiplayer. If one of your party members falls, you can use a resurrection potion to bring them back to life right there, but you may want to wait until the area is clear of monsters. Resurrecting another player takes a few seconds, during which you're defenseless. This saves your friend needless run time and keeps the action moving.
Each of Diablo III's character classes has its own unique playstyle, and the barbarian, witch doctor, and wizard have picked up a lot of new tricks since last BlizzCon. What are some cool new spells and abilities that players should try out?
Jay Wilson: First up, the barbarian has a new ability called Revenge. Whenever the barbarian takes damage, he has a chance to be able to use the Revenge skill, which will inflict area-effect damage on nearby monsters and restore some health to the barbarian. This ability is extremely effective once you're in the thick of battle, as it lets you dish out and recover damage all at once. It lets you stay at the very front lines, drenched in blood and completely surrounded by screaming hordes of enemies -- just the way barbarians like it.
We've added a lot of control abilities to the wizard's bag of tricks. You can slow down enemies with Frost Nova, push them back with Wave of Force, distract them with illusionary mirror images, or cover yourself in impenetrable rock with Stoneskin.
The newest witch doctor ability let you summon spiders from a zombie corpse in the ground. The witch doctor can also haunt enemies, creating a wandering ghost that sucks the life from all those pesky demon types.
Part of the excitement of playing Diablo comes from the constant hunt for more and better items. Should players keep an eye on item drops in the BlizzCon demo, or will characters already come with excellent gear? Are there any "must have" drops to look out for?
Jay Wilson: The item-hunting and gearing-up game of Diablo III is hard to reproduce within the demo's limited timespan. That being said, we accelerated the drop rate for the demo, so hopefully players will at least get a good feel for what the loot aspect of the game will be like.
This demo also features the new group loot system that I’d mentioned earlier. The way it works is really simple: If you see something drop, it’s yours. Every player gets their own version of the loot drops, so you'll never see someone else's stuff, unless a player decides to drop an item themselves.
As far as hunting for upgrades is concerned, the characters will start off with pretty good gear, but there are definitely going to be some really nice replacements to be found throughout. Players should focus on rare items, which are the ones whose names appear in yellow, as these will definitely be upgrades. Also, if an item is neither white nor blue nor yellow, you absolutely, positively want to pick that up, because that means you've found something super-rare.
Of course, there's one white item in this demo that is very special indeed...you'll know it when you see it.
BlizzCon Diablo 3 Panels
What are you discussing in the Diablo III panels at BlizzCon? Will players learn things from the panels that they won’t find in the demo?
Jay Wilson: I think Diablo players will get the most out of BlizzCon by going to the panels and checking out the demo. They complement each other very well; I think you'll be able to get more out of the panels if you can see the game in context, and I'm sure there are some things in the demo that we won't have time to cover in-depth in the panels.
This also ties into our general philosophy for this year's demo. Last year we showed a complete, self-contained setting where players were dropped into a dungeon, fought through it, and took down a boss in the end. This time, we want to present a slice of gameplay -- here's a large area with quests, hordes of cool new monsters, scripted events, random encounters, and lots of loot. It's much more open-ended than last year's demo, and I believe this will give players a good idea of where we currently are with the game.
Of course, one thing to keep in mind is that Diablo III is still in development, and there’s still lots and lots more to come beyond what’s at BlizzCon.