We're sitting at the Diablo III gameplay panel and will be documenting the key features. After sitting down and playing some with Rapture and Frst, I can assure you that it is going to be awesome.
Diablo III Design Goals
Stay true to Diablo experience. Has the same feel of the existing games.
Moment to moment action should feel exciting and important.
Diablo is an Action RPG, and we want to expand the RPG experience.
New rune system for augmenting skills.
Spirit of Diablo
Make it replayable more than just randomness (items, maps, etc.)
Large scale boss battles.
Focus on cooperative play, making it easy for people to jmup in and out.
Random Monster Encounters.
Randomly Generated Items.
Higher Difficulty Levels (Nightmare, Hell, and more?)
New Feature: Random Adventures.
Large scale combat putting as many monsters on the screen as possible that you can pile into the dirt.
All classes will be incredibly powerful, unique, and approached in a new way.
Easy to play (If you can click a mouse)
Easy to learn, but difficult to master.
Battle.NET - New version that should make it easier to play together.
It should be easier to hop in a game with your friends at any time.
Less Spam, More Depth.
New Type of Monster (Not specified)
Removed potions as primary health mechanic.
Replaced potions with a skill hotbar.
Better gameplay, less mouse clicking wrist pain.
New Health System
Goal is to remove things from D2 that made it too easy (potion spamming).
Very little downtime.
Monsters drop globes of health that you run over to restore health.
Health globes automatically heal nearby teammates.
Monsters - Force Players to Make Choices
Berserker - Aggressive Creature, Massive Charge up Attack, Vulnerable on a Miss.
Skeletal Shieldbearer - Slow and methodical but tough, Accompanies ranged units, Acts as a health wall for more threatening units, Shield can be destroyed or circumvented.
Improve story without losing the ability to hop into a game easily.
Remove the generic feeling from random dungeons.
Bring the world to life through events, better quests, and npc interactions.
New Adventure System
Solution to the fact that scripted events don't work with random environments.
Smaller scale encounters that randomly occur.
Each play through can feel different as you won't always get the same adventures.
Question and Answers
Q:Will there be a hardcore mode?
A: Yes, definitely.
Q: Will there be talent respecs?
A: Yeah, we definitely want to have talent respecs this time around. Details have not been worked out yet.
Q: How will the economy work in Diablo 3?
A: I think the D2 (SoJs) economy turned out the way it did because of the gold cap and how much gold the mods dropped. We want the gold you have to be meaningful. We want players to be able to use gold as a trade currency, but no details at the moment.
Q: What kind of PvP system will be in place?
A: Diablo II system didn't work. They don't have a solution yet but plan to come up with that satisfies both PvE and PvP focused players.
Q: Are you going to removed the complete immunity system?
A: Class builds are going to have much more variety so that immunity will no longer be a problem. This means immunity will most likely still be in the game to incentivize you to build a more diverse character.
Q: How will the scramble for loot work?
A: Loot is per person specific. If you can see it, only you can loot it. Something drops for everyone. Items can still be traded per characters. Loot dropped can be seen by everyone.
Q: Will we need to stack magic find and run bosses over and over to get loot?
A: Magic find will continue to exist. We want to make it so you can still get good loot without running the same boss over and over.
Q: Will there be special achievements by your name to show you have beaten the game on hell mode?
A: Yes, we will do something.
Q: Will all classes have as much environmental interaction as the wizard?
A: I think the answer is yes. Every class is different, but the wizard does feel a bit more destruction. Later on all classes start getting something for interacting with the environment.
Q: How many players for coop?
A: We are finding that 4 is about the perfect number to prevent the gameplay from becoming too chaotic. Still up in the air though.
Q: Is there going to be a ranger or something?
A: Wirt and the Cow King are the other two classes.
Q: Any way to customize the appearance of your character?
A: We tried hair changes, skin tone, etc. You can't really tell because the character is so small. We don't really have an incentive to keep those systems in. We want to create more permutations in the looks as we aren't really happy with the level of customization in the game.
Q: Diablo I felt more fragile than Diablo II. What will Diablo III feel like?
A: We see Diablo III as a blend of both games as there are things from both that we like. We changed several things such as the health system to help give the "I'm trapped in a dungeon with a lot of monsters around" feeling.
Q: How will Diablo III multiplayer differ from single player?
A: We're not focusing on persistence as a primary goal. It makes the drop in and out coop play harder to achieve. We do want to make the world feel like it is transitioning. There will be big milestone events where the world changes.
Q: Is there a crafting system similar to the Horadric Cube?
A: I'm not going to say yes or no. We are exploring an item creation mechanic. The Horadric Cube was actually kind of annoying of a mechanic. We want to make a mechanic that is better. More space in the inventory and ways to upgrade it.
Q: How do we make sure players diversify what stats they use?
A: I don't think it is possible to make sure every class wants every stats. We want to make sure every stat is useful across all classes.
Q: Are there still super rare items?
A: Yes. Randomly generated items are still at the core of the game.
Q: Will security be ramped up?
A: We will have much better security.
Q: Will there be raid encounters?
A: Goes against what we want. Maybe we could see end game content, but we won't have WoW style raiding where character classes have roles. Raid system really doesn't fit the Diablo style of having all dps classes.
Q: Will there be an auction house?
A: Auction houses are cool, but might make items too accessible. We do want a trading system that is appropriate for Diablo.
Q: Will Battle.NET remain free?
A: We don't have a strong desire to make Battle.NET be a subscription service. We do plan to monetize it somehow. It shouldn't feel like a bad thing to the players.
Q: Will items become soulbound?
A: No there will not be a bind system. We want players to be able to trade items freely. There might be quest items that bind, but we really don't want to.
Q: Are there ways to do damage once you run out of mana?
A: We want the game to be fast paced so that you don't sit around with no mana a lot. We want to have skill based ways to actively get mana back. If you have to step back for mana it is for a couple of seconds, not minutes.
Q: Will there be synergy between spells or combos?
A: We want to make sure no one spell dominates. We want to have a mix between buffs and actives. Example: Witch doctor summons creatures and he can cast plague on them.