The remastered release of a game covers such a wide spectrum that it can go from looking like a simple re-release in one example to a borderline remake in another. This of course can dictate the potential response from fans and the wider community -- especially when dealing with games that are brought back from an era where displays were as hefty, thick, and non-HD as the baggy pants and jeans people were wearing at the time.

Like an archaeological find discovered in the dunes of an unkempt garage, or simply a means to re-introduce a classic to a new audience, the idea of a remaster is never a bad thing in and of itself. In fact it’s often cause for celebration. Case in point, Diablo II: Resurrected. Which sees the Y2K hit from Blizzard North find its way to modern consoles and PC hardware later this year.

When rumours began to pop up that Blizzard were actively working on or toying with the idea of bringing back the iconic action-RPG -- many began to wonder exactly what that might look like. Would the 2D sprite-based visuals of Diablo II be given the 4K makeover ala StarCraft: Remastered, or would it be more of a built-from-the-ground-up remake with new visuals and perhaps reimagined content too. Questions that arose due to the game’s pedigree.

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Describing Diablo II as iconic isn’t merely a random descriptor, it’s a seminal release that not only helped define a genre but laid the groundwork for a future where loot, real-time action, player progression, and things like builds and weapons and character classes became ubiquitous...

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Describing Diablo II as iconic isn’t merely a random descriptor, it’s a seminal release that not only helped define a genre but laid the groundwork for a future where loot, real-time action, player progression, and things like builds and weapons and character classes became as ubiquitous as military shooters that focused on gruff soldiers with assault rifles. In fact you could probably trace Call of Duty’s multiplayer progression systems back to Diablo. Probably.

At BlizzCon last month, when we got our first glimpse at Diablo II: Resurrected, the surprise came not from the announcement itself but in how the execution seemingly exceeded all expectations. Impressive, modern 3D visuals that stay true to the look and feel of the original. Visuals that sit on top of those classic 2000-era pixels, presenting a radical visual makeover that preserves what makes Diablo II, well, D2.

A 3D Layer on a 2D Core

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“It's a different kind of challenge,” Rob Gallerani, Principal Designer on Diablo II: Resurrected tells us when asked about the decision to go 3D whilst keeping the 2D core. “I will argue that it is easier than trying to rebuild brick-for-brick the entire game. I would rather take the Sistine Chapel and rotoscope over it then be like here’s a bunch of pictures, go build it over here. It does have unique challenges because we are seeing behind the curtain.”

For Diablo II: Resurrected, which includes the base game and the Lords of Destruction expansion, one way to think about it is in that rotoscope or tracing sense. Using the underlying assets and game as a means to drive the 3D layer. On top of taking each and every element and recreating it, animating it, adding textures, and lighting too -- the challenge mostly derives from the very nature of going 3D.

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“When you have a sprite-based 2D world it's a flat thing on a flat thing. And now you have stairs with elevation, you have undulating ground that a sword has to fall onto. Even simple things like readability become a challenge."

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“It's the 2D to 3D world translation,” Rod Fergusson, Executive Producer on Diablo II: Resurrected adds. “When you have a sprite-based 2D world it's a flat thing on a flat thing. And now you have stairs with elevation, you have undulating ground that a sword has to fall onto. Even simple things like readability become a challenge, like a Paladin’s Aura. The way that you can see the Aura very clearly lets you know you have that particular Aura. What if you’re walking through a grassy field and the aura is being blocked by grass because that's 3D now and it’s physically on the ground and growing up through the Aura. Well, you’ve gained realism but lost a certain amount of readability and clarity. And there’s clarity in Diablo II’s 2D world.”

“The background could be fancy pillows, it could be piles of skulls, it could be sand dunes, but it's really just a flat image,” Rob Gallerani explains. “When you drop a sword, that's a 2D sprite. It's just a flat sprite and it sits on top and you will see it. When we have a 3D sword resting on 3D skulls and bumpy things, we can't just have it be there because it would clip through all those things. So we need to make sure that it renders on a pass that's on top of those things. There's a lot of loose ends that all need to be accounted for when you're bringing a 2D sprite into a 3D world.”


And it’s that aspect, having the 2D world drive the 3D layer that ensures the team preserves the game as is. Even with adding an impressive visual makeover, controller support, and a modern widescreen presentation that supports 4K TVs and ultrawide PC monitors, it’s the same Diablo II it has always been.

“Everything is being positionally driven, statistics wise, or otherwise by that same 25 frames-per-second-logic cycle,” Rob continues. “The simulation on top of it, divorced from that, we can have an uncapped frame-rate for animation and other things. That’s why it’s one-to-one, even though it's really just one and you're getting to see this other layer on top.”

In The Beginning

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Where does the process begin? If you were to take an existing 2D game and all of its assets and not only recreate the visuals in 3D but retain the core code and make that work across multiple platforms and input methods -- there would naturally be a to-do list. If the game was twenty years old, that to-do list probably includes finding anything and everything to do with the game’s development.

“We have a producer, Matthew Cederquist, and my fellow designer Andre Abrahamian, they literally went to all the physical warehouses looking through filing cabinets,” Rob Gallerani recalls. “People actually had filing cabinets at some point in their life. It was also going through people's desks. They would find folders on drives that were just called, ‘We should probably back this up at some point’. Old marketing materials. It wasn’t easy, but it was very exciting.”

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“Everything is being positionally driven, statistics wise, or otherwise by that same 25 frames-per-second-logic cycle. The simulation on top of it, divorced from that, we can have an uncapped frame-rate for animation and other things."

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“In addition to the physical envelopes and binders we found stuff in the code too,” Rob Gallerani says of the other side of the equation, Diablo II’s source code. “Diablo II is running on an engine that goes back to the original Diablo. So we had moments where it was like, why is this in the engine? And then you're like, ‘Oh, a light radius used to matter in Diablo one’. There’s a torch, there's body parts. What was a little crazy was because of the nature of how we were like let’s take all the art and make it 3D, we actually started making 3D assets for content that wasn't even used or was turned off.”

“Then we realised we at least had to do a pass,” Rob laughs. “There's probably a couple of things modders will find where they’ll be like ‘We could use that item’.”

Above all though, that is getting the code, art, and 2000-era 3D assets (as Diablo II’s sprites were based on old-school 3D rendering) it was all in service of getting a better understanding of the game itself. A fact bolstered by having people at Blizzard today that were part of the Diablo II development team to draw on.


“We’ve been focused on developing from a perspective of ‘What if they had these tools today, back then?’” Rod Fergusson says, when summing up the process behind remastering Diablo II. “What would they have done and how would they have done it? This archaeology, of digging through old assets and code has helped us understand the intention of the original creators. We want to be respectful to that vision because it's awesome. We love what Blizzard North did and we're just trying to make sure a new generation gets to play it.”

This extends to the cinematics, where all 27 or so minutes of 2000-era CGI is being rebuilt from the ground-up by Blizzard. And with Blizzard’s expertise in the field of pre-rendered cinematics going as far back as Diablo II this is allowing the team to look at those assets and reimagine them with 2021-era detail. “There's this notion of symbology that might have been a little muddy in the original version,” Rod notes in reference to the CD-ROM style cinematics found in the original release. “Being able to find the actual textures, the art of what that wall should look like, and what the intention would have been if they were able to render it at a higher resolution -- is great.”

The Iconic Action-RPG

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“The sheer amount of time it takes you to take a character to max level in D2,” Rob Gallerani pauses, when the discussion shifts to Diablo II’s mechanics and systems. “It’s just a much longer tail to get to what you would call the ‘end game’. And pretty quickly in that span things like Identify Scrolls are not a thing because you have Deckard Cain and Stamina isn't really a thing because you've gotten enough Vitality that you forget about it.”

It’s a seemingly simple thing, pointing to how Diablo II changes over the course of several hours -- with systems and mechanics that evolve or drift into the background. During early playtests, where the team dove into Diablo II, the Stamina question would come up a few times when some began wondering why they were suddenly walking. If it’s been a minute since you’ve played Diablo II, you might also be thinking ‘Oh that’s right, Diablo II has Stamina’.

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“We’ve been focused on developing from a perspective of ‘What if they had these tools today, back then? What would they have done and how would they have done it?'"

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“That's the experience you go through as you level these characters,” Rob Gallerani adds. “These systems just touch everything.”

With Diablo II: Resurrected hitting just about every platform you can think of -- from PC to Nintendo Switch to next-gen consoles and the PS4 and Xbox One -- with cross-progression support (the team isn’t quite ready to talk about its plans for cross-play quite yet), naturally you’ll be able to control the on-screen action with a controller.


As seen in Diablo III’s transition to the console space, of which Rod Fergusson agreed when we posited the theory that it arguably plays better with a controller -- “not arguably, it's better on console” -- it might be safe to assume that the transition here would follow suit. But, in retaining the core Diablo II experience keeping things like inventory management in-tact and something like Stamina that not only depleted but also factored into how other stats behave revealed just how much thought would need to go into even the simplest of ideas.

“When we put movement on a thumb stick for a controller, what’s traditional is you push the thumb stick a little and you move a little bit and if you push the thumb stick a lot you run,” Rob Gallerani explains. “And we were like let's do that. The problem is, nobody ever pushes a controller stick forward just a little bit -- you push it all the way. And in Diablo II your stats actually change when you run, people forget but your Armor drops when you run.”

“What we then did was what you find in modern shooters where you click the thumb stick and that's what toggles between walk and run,” Rob notes. But even this brings up another issue relating to picking up an item off the ground -- where the precision and the granularity of a mouse is often hard to replicate. “With normal pathfinding, if you click on a potion, you'll run to it and pick it up. We actually allow you to pick potions up behind you when you're using a controller, because people will run past an item.”

Making Changes - An Inventory Story

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“A lot of times we would have discussions about making changes,” Rob Gallerani says. “Maybe we should try this rebalance. Some of the easy ones we would test we’d be like, ‘What are we doing? This is different’. Maybe it's a cool direction to go but it's not the original.”

Part of the process that is remastering Diablo II for Blizzard was to stay true to the original, and to ensure what is important to fans was still there. So right off the bat sweeping fundamental changes were never really on the table, though the idea of increasing inventory size was briefly discussed and then quickly dismissed based on just how key inventory management is in Diablo II.

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“A lot of times we would have discussions about making changes. Maybe we should try this rebalance. Some of the easy ones we would test we’d be like, ‘What are we doing? This is different’. Maybe it's a cool direction to go but it's not the original.”

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That is sacrificing room for Charms, being specific about how many Potions you can carry, decision making on par with combat, exploration, and assigning Skill Points.

“Where we did a lot of experimenting was when we were looking at quality of life things or adding things for consoles,” Rob adds. “When we added a controller one of the things that we tried was an auto-sort of the Inventory for people. We'll keep the Inventory Tetris but because managing your inventory might be difficult with the controller we'll just do it for you. And so we did that. We built a system where as soon as you got an item, it would go in your inventory in the most optimal way. It would automatically sort it for you. That was in the game for maybe five minutes.”

“It took me 10 seconds to write that email to Rob going, ‘What are you doing?’” Rod Fergusson intejects with a smile. “Please stop doing whatever this is.”


“Not only did people not like that the game was doing it for them, but that it would rearrange their own sorting method,” Rob Gallerani continues. “They'd be like, ‘I want my Tomes on the left side, and my Potions on the right'. Then they'd go and pick up one item and it would sort it all and it was rage-inducing. This is clearly something that is part of Diablo II so why are we even meddling with it?. Let’s just keep it as is.”

Diablo II: Resurrected isn’t devoid of changes, quality of life improvements like a shared stash is coming, alongside the option to make gold-pickup automatic. Even the above auto-sort for inventory will be optional. Again it comes down to staying true to the original vision, it’s why the fancy 3D overlay is simply just that. And for a game as revered as Diablo II -- fixing something that could be labelled a ‘bug’, ‘exploit’, or ‘glitch’ carries with it additional weight. Thankfully the fact that people still play the game today means just about everything has been discovered, discussed, and dissected by the community.

“We're still going through and making choices of ‘Oh, do we fix this bug?’ ‘Do we change this bug?’”, Rob explains. “And really when it comes to fixing something that's a bug, the first stop is the community. And over the years they’ve been very vocal. They write everything down. So in a sense it's pretty easy for us to be like, ‘This has been around for 16 years and they've talked about it at all these places’.”

“We have a pretty good idea of whether something should be fixed or ‘Here's a strategy, and here’s how you can make a build around this’”, Rob continues. “And we didn't want to put a stop to that. The other thing is that if something was a bug, but the way that we fix it impacts all these other systems then that's too risky of a change to make. That’s kind of where the line is, but we're still working through those things even now.”

Back to That Impressive 3D Layer

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Diablo II: Resurrected’s biggest change of course is the visual makeover, a 3D layer tailored for multiple resolutions, aspect ratios, and something that can also scale easily across a wide range of hardware. Being able to play the game in handheld mode on a Nintendo Switch or on a big-screen 4K TV is no doubt something to be excited about.

And for a PC game from twenty years ago, the flexibility of the new 3D layer adds additional options for the team -- zooming in a little for those sitting on a couch, increasing text sizes, opening the frame to present more of the impressive environments for widescreen displays. Scaling detail levels and frame-rates, remastering both the music and audio (with the original voice work intact) for surround systems and modern headsets.

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"When it comes to like fixing something that's a bug, the first stop is the community. And over the years they’ve been very vocal. They write everything down. So in a sense it's pretty easy for us to be like, ‘This has been around for 16 years and they've talked about it at all these places’.”

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That said, getting the 3D makeover to look as good as it does took considerable effort beyond bringing all the 2D assets over.

“Some of the first games I worked on were isometric sprite-based games,” Rob Gallerani recalls. “When you look at a sprite going up against a wall they're faking the fact that a character looks in front of some pieces and behind other pieces. And the way that you do that is you actually create a small amount of distance from the wall. If you know the Diablo II mini-map you'll know that your character is like a little ‘X’ on the map, a little plus. In actual fact your character is that plus, you're not one block you're five blocks. And that's to make sure that you're a certain distance away from a wall.”

“We don't get to do that because we really are in 3D,” Rob continues. “The same goes for some of the effects where the old game just did a pallet swap. Take all of the colours and flip them so now you're using a different set of 16 colours. We can't do that, we have normal maps, texture maps, real-time lighting. It's entirely different technology.”


“The way a character turns green when they get poisoned -- armour and all,” Rod Fergusson adds. “It had no basis in reality, it looks like your armour's poisoned too. When you have a physically based render, that's really focused on how materials react to light. So the idea of painting them green to showcase poison, there's more nuance to it in relation to getting that same clarity. Stuff like a sword that now has an ice ability. That becomes the tricky part.”

Interestingly whilst the 3D visuals present visual effects and physics and 3D objects that interact and react to lighting and other elements, there was always a conscious effort to ensure that the original look and feel was always maintained. The little ‘X’ on the map, the buffer that can result in no actual collision happening between sprites in the original game -- sums up the approach taken with Diablo II: Resurrected.

“You didn't really notice things like collision because it was a point and click game,” Rob Gallerani explains. “Let's say you have a wall in front of you and the end cap has collision or doesn't have collision. You click on the other side of the wall and your character walks around it. More importantly the character walked around the collision for you."


"So you didn't really notice that it clipped the corner or it took it a little wide," Rob adds. "When you're using a controller and you can just run into the wall and rub up against it you'll notice every little thing. This is another point where we were like, we're not changing the collision because that would be changing something core to the game. And to be honest we’re sitting there thinking, what does it matter? One wall here. But it’s a slippery slope right? No collision has changed and no art has changed, we're incorrect in the same exact spots where it was before.”

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Diablo II: Resurrected’s biggest change of course is the visual makeover, a 3D layer tailored for multiple resolutions, aspect ratios, and something that can also scale easily across a wide range of hardware.

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And this might be the magic of Diablo II: Resurrected, a remaster that at a glance looks like a remake. The same game from decades past, now looking better than ever whilst being accessible on basically every platform. A resurrection in name and execution.

“To say that not only do we totally understand every little thing but then recreate it,” Rob concludes. “There would definitely be human error. We're very good at what we do, but we're not that good. This is what it was. We can't mess up. We just have to essentially make sure everything has 3D counterparts. And that D2 stays D2.”