Designing Diablo III

I think one of the key things is you have to understand and accept true randomness. A lot of times [people think that] whenever an item drops sooner than it seems like it should, or you get like eight swords in a run, the loot system's totally broken. No it's not, it's random. That's what it's supposed to be. It's supposed to be unpredictable.

It takes a lot of getting used to. If you play a game that doesn't have randomness like that, the result is generally going to be the result; and so you can play it, judge the result, make a change. With randomisation, you have to play it, play it, play it, play it, play it, think about it, play it, think about it, play it, make a change. And then repeat. You can't be too reactionary.

So it makes the tuning process more involved, but you get so much out of it. Once you get those systems going, it's a game you can play over and over and over. You get far more bang for your buck, but that initial investment in tuning is tough.

We're trying to - as long as we can come up with original and cool mechanics for each one. Right now, all the classes have unique resource mechanics but some of them are more successful than others.

The Monk one's probably the one that works the best. I really like it. It's called spirit, he gets it through combo moves, it builds up slowly, and then he's got certain moves that use up spirit.

So it's all about building it up over time and really thinking about it: "Do I want to use my awesome attack power here for a lot of damage, or save some because I have a really good skill for getting me out of trouble?"

There are some interesting decisions to make there, but it's not so frequent a decision that it feels like you're staring at it all the time, which is one of the problems we've had with some of the mechanics.

The Barbarian we're still working on, we still haven't gotten Fury just right. Mostly it's dealing with exactly that issue - you feel like you have to manage it all the time. Each class is a different challenge.

Yeah, I think we look at a couple of things as not good enough. Whenever we decide to make a game, especially if it's a sequel, it's always because we look at a game that we've made or a genre that we like that we see flaws and problems in. And we go, "We want to fix that. We love it, but it would be even better if it was like this."

So when we looked at Diablo II, the main things that we really focused on were: the combat model doesn't have as much depth as we'd like; it can be a very simple, one-button game, and that can be good, but we'd kind of rather it be a mostly one-button game and occasionally a three- or four-button game. That's got more depth, it's more interesting, it's got more mechanics to it.

And that funnels down into class design and monster design; when you've got more mechanics to play with, they can be deeper as well. That's why we changed the health system, that's why we created the skill hotbar, that motivates a lot of the changes we've made, right down to the resource mechanics also.

The other side is story. This genre, even though half of its blood is RPG which is a story genre, most of these games are not very story-intensive or don't tell great stories. So that's something we really wanted to focus on: creating a world where story is pervasive, that felt like as you moved through it, even though it's randomised, there are events occurring that tell you what's happening in the game world.