Evolution of Unreal Engine

Humans are by far the hardest part of computer graphics because millions of years of evolution have given us dedicated brain systems to detect patterns in faces and infer emotions and intent because cavemen had to, when they see a stranger, determine whether they were likely friendly or they might be trying to kill them. And so people in the world have extraordinarily detailed expectations of a face and we can notice imperfections, especially perfections arising from computer graphics limitations. Okay, one part is capturing humans and so [inaudible 00:00:33] really advanced, dedicated hardware that puts a human in a capture sphere with dozens of cameras in them taking high resolution, high frame rate video of them as they go through a range of motions. And then capturing the human face is complicated because the nuanced detail of our faces and how all the muscles and sinews and fat work together to give us different expressions. So it's not only about the shape of a person's face, but it's also about the entire range of motion that they might go through. So that's the data problem. There's a lot of other problems with computer graphics. There's technology for rendering hair, which is really hard. Because you can't render every... Again, we know the laws of physics. It would be easy to just render every hair. It would just be a billion times too slow. So you need approximations that capture the net effect of hair on rendering and on pixels without calculating every single interaction of every light with every strand of hair. That's one part of it. There's detailed features for different parts of faces. There's subsurface scattering because we think of humans as opaque, but really our skin, light travels through it. It's not completely opaque, and the way in which light travels through skin has a huge impact on our appearance.

The following is a conversation with Tim Sweeney, a legendary video game programmer, founder and CEO of Epic games that created many incredible games and technologies, including the Unreal Engine and Fortnite, which both revolutionized the video game industry and the experience of playing and creating video games. This is the Lex Fridman podcast. To support it, please check out our sponsors in the description. And now, dear friends, here's Tim Sweeney. When did you first fall in love with computers and maybe with programming?

I had a brother, Steve Sweeney, who 16 years older than me, and at some point when I was a little kid, he went off to work in California for a tech company and he'd gotten one of the first IBM PCs. And so for one summer, I think I was about 11, I went to visit him in California. It was my first trip away from my family just to hang out with him and he had this brand new IBM computer and I learned to program over the course of a few days in BASIC. I was just blown away with the capabilities of computers at the time. It was unbelievable what they could accomplish, and I just was hooked from that point onward and very much wanted to be a programmer. Do you remember what you wrote in BASIC? Is it a video game type thing? Is it like for loop, some numerical thing? Do you remember?

10 to 15,000 hours. What was the value of the hours as a kid you put in in programming that led to the success you've had in later life? Maybe this is by way of advice to younger people in terms of how they allocate the hours of their early life. Yeah, it's not just hours. It's really striving to learn, to understand what knowledge you have, what knowledge you lack, and to continually do experiments and work on projects that improve your knowledge base. And I didn't do this with a great amount of structure or planning. I was rather just going from project to project, doing things that I thought would be fun and cool. And with each project I learned new things, learning about how to store and manage data, learning how to deal with advanced data structures, how to write complex programs that have deeply nested data and control flow. Each one of those provide a lesson which were later essential. In 1991, I released my first game and over the course of that decade went from zero commercial releases to the first generation Unreal Engine. But this was largely just using the knowledge that I'd built up over the previous decade, just doing fun hobby projects. And if I hadn't done all of that work, there's no way I could have ever built the things that came later.

So on the video game side, when did you first fall in love with video games? I've had a funny relationship with games because my real aspiration has always been to program cool stuff. And I get more enjoyment out of programming than anything else in the world. And so my first really two formative experience with games were playing this game called Adventure for the Atari 2,600. It was like you move this dot around the screen and picked up objects like swords and fought dragons and invaded castles and solved puzzles. Very, very simple iconic stuff rather than realistic graphics. And then the other game that I really got immersed in was Zork, which was a text adventure game. It would tell you where you are and what you see and you type in commands like go north or pick up sword or open door and explore a world that way. So the game didn't have any graphics, but in your mind you had this elaborate picture of what you were seeing there, and it really brought in [inaudible 00:16:09] inspired imagination more than other things.

So take me there in the early 90s, so you launched Epic Games in 1991, so the writing of your first big video game ZZT, what was it like? What was the technical challenges? What were the psychological challenges of building that? It was a funny project because I didn't start out to build a video game. I'd just moved from an Apple II, so my brother bought my family an Apple II right after I'd visit him in California. So I've been programming on that for a few years, learned a lot of techniques, but weren't many Apple II users around still by the time that cycle came to an end. [inaudible 00:17:56] so I'd just gotten an IBM PC of my own and was learning to program and I realized I needed a text editor. So I started writing a text editor. A text editor is a program to edit text files. You have logic to move the cursor around and let people type things and backspace and delete and do all of those mundane actions. And one night I'd finished it up and I was like, well, okay, I have a text editor, but this is pretty boring.

Yeah, it's fascinating. I mean, pirates do lead the way for innovation, the same as the story of Spotify. Basically, I think, most people when they derive value from things like video games, want to pay for those video games, they just want it to be easy. And so the same thing with music, with Spotify. But maybe just staying on the 90s, there are going to be a lot of indie game developers who will listen to us talking today. Can you go back to that mindset and try to derive some wisdom and advice to those folks when you were just a solo developer or maybe just a small group of people creating your early games that eventually became this huge gaming company. But in the early days, what were you going through? What were the ups and downs? What did it take to stay strong and persevere? Well, one of the critical things that Epic always worked hard to do was to make something different that nobody else was doing, and to try to satisfy a small audience rather than competing globally with the game juggernauts. Back in the 1990s, Epic was new, but Electronic Arts and Activision and the other big publishers had been around for a decade, and they were huge companies. It had giant retail distribution networks. If I tried to make a game and then convinced them to publish it, I doubt I could have had a chance. And I doubt that even if I had made a successful game, that I would've made much money from it, though they might have. And so the really unique angle to Epic then was shareware. And that was just the idea that if we distribute our game differently, then we can reach a much larger audience than these bigger competitors by virtue of this first episode of the game being free.

So I'm sure people know, but Epic Games was created in 1991 and went on to transform the gaming industry several times, one of which is Unreal Engine. So let's talk through the origin story of that. You said that when Wolfenstein and Doom came out, that changed everything, so take me to that moment. Yeah, that was a very interesting time. Epic had, after my first couple of games that had recruited developers, usually college students, high school students who were just working on their own, had real skills but didn't have an outlet for their work, Epic had been matchmaking the best artists and programmers together from all over the world. Like Chaz Jackrabbit was Cliff Bleszinski, a high school kid in California, had made a really cool adventure game together with Arjan Brussee, a demo coder from Holland, who would make amazing graphical stuff and had built a 2D game engine. They had connected them together, and a musician, Robert Allen in California. And by telephone and modem and so on we were building these little 2D games and having quite a lot of success. There were a bunch of people making thousands of dollars a month while they were still students in royalties from the games the Epic was producing and by coordinating with people and publishing through shareware.

Unreal Engine is this fascinating creation. It's a big, bold, crazy bet that you've made. Maybe it's good to actually explain what Unreal Engine is for people sort of outside this world. I would say it transformed the gaming industry. But that was a big bet in 1995, that most of the effort would be on creating the gaming engine, not the game. Yeah. A new engine is a big bundle of code and tools, a huge software package that provides all the functions you need to build any sort of a 3D graphics application. Game developers use it to make games and that's the predominant use. But it's also used in Hollywood film and television production to create 3D scenery in real time for production sets, to do a pre-visualization. It's used by car makers to visualize their cars before they're constructed or manufactured. It's used by architects to preview buildings before they're made and industrial designers of all sorts. And it provides all of the 3D simulation features you need, both for creating highly realistic 3D graphics, but also physics and interactions between objects and making things happen like you might see in the real world. And supports a huge variety of styles, from Pixar stylized movies to cell shading to photorealism. And it can be used for anything that needs real-time 3D graphics.

Can you just go back to that, you programming. What are some interesting technical challenges you had to overcome? You mentioned dynamic lighting, create this three-dimensional world and try to figure out the puzzle of how you actually do that at a time when nobody, Carmack and you, doing this kind of thing. It's a totally open Wild West. So what are some interesting technical challenges you have to try to solve? There's a lot. Some of them are visible on screen and some are behind the scenes and still require a lot of innovation. All of the graphical techniques were really interesting challenges. And Unreal Engine in those early days went a lot further than the Quake engine and building environments using constructive solid geometry with a real-time editor. And that was a really interesting technical challenge. The idea is building is extremely tedious if you are only adding objects to the world. If you want to build a door, then you need to add like a dozen different pieces of door frames and add a bunch of different walls together to fit together in the right shape. It sure would be easier if you could just start with a wall and subtract the door out. And so we had this way of adding geometry to the world and subtracting geometry and the engine would perform all of the calculations on that. And this is something that I'd been anticipating was possible for-

What about lighting? Is there other interesting- Well, the funny answer is we know the laws of physics, so it's actually really easy to do everything in computer graphics, but the direct solution of the laws of physics is immensely slow. What we're finding are approximations rather than complete solutions because you need something that's a million times faster than the brute force answer.

This is blowing my mind. This is so fun. What about fog? You mentioned fog. How do you even do fog? You mentioned Unreal, so the first version had fog. Yeah, it was a funny thing. This graphics hardware company had just started up in Finland and they released a screenshot of what their GPU was doing, and they showed a scene filled with volumetric fog. They had a foggy room with some light sources in it. When that happens in the real world, what you see are glows around the lights as the light brightens the fog around it, but the brightening of the fog diminishes over time because the fog absorbs some lighting. The further you get away from the light, the more fall off there is. We have a bunch of colored lights overlapping together in a space like that. The effect is just absolutely magical, like being out on a foggy light with street lamps above. It's something that's surreal and looked just beautiful. I was like, "Oh my God, they figured out how to do real-time volumetric fog. I have to figure it out myself." That was another 30-hour coding session.

John singularly has this intense dedication to getting the best result from his code and having absolutely no attachment to passcode and some of the legendary things he did. The end result was an absolute breakthrough in real-time computer graphics, weren't his first try. They were like his seventh or eighth try after he'd done something time and time again, tried it, found a better approach, thrown out the old one, built it again, and continually rewrite his code until he found the absolute best solution to a problem. I think that stands as a lesson for every programmer to pick up on. When something is really, really important, its performance is absolutely critical to the product or its quality or its capabilities. Just iterate on it until you've achieved perfection and don't settle for the first or second solution is good enough. The result of that both you and him sort of define the future of gaming, of gaming worlds. It's so beautiful to see. It's just fascinating. It's inspiring because under so much uncertainty, under so many constraints, you figure out a way. That actually continues to this day because yes, the hardware is improved incredibly, but in order to create an ultra realistic, highly dynamic, real time rendering of the world around us, it's still really, really difficult. There's all these kinds of optimization, like you mentioned. Maybe you can speak to that Unreal Engine One journey from one to 5.5 or .6 now. For 30 years, you've been creating virtual worlds. What's it like evolving a game engine for those 30 years when the hardware under you is improving exponentially? What are some things that changed and what are some universal truths that have not changed?

That's in part, we'll talk about it, why maybe you have to rethink even the programming language that's being used to rethink a lot of things. That's fascinating. Can we just stick on Unreal Engine Five? I watched a bunch of stuff, but the state of Unreal in GDC 2024. I was just giggling with excitement watching some of this stuff. If we can talk about different things here just to nerd out a little bit. People should go watch this video. They talked about the dirt. The ultra-realistic, and this is for Marvel 1943, which is kind of putting the Marvel universe into Nazi-occupied France in the winter. There's snow, and that's a moment in history. That's a very intense moment in history, and it really creates a feeling and puts you there. There's so much to that, including the snow. Just looking at the dirt is a really nice way to show how do you add a lot of details to the scene in real time that gives this experience infinite detail? This is real, this is super real. Then I think in the talk they describe what's entailed in the generation of the geometry, what's entailed in the lighting, all that kind of stuff. Maybe can you speak about dirt? What are the components for people who might not know in creating this ultra-realistic, the texture, the lighting, the geometry, all of that, how Nanite, how Lumen all come together in this beautiful orchestra to paint in real time, the dirt in Nazi-occupied France in 1943?

Okay, so I got to ask you about the humans. We talked about what's it like to create the scenes, but creating realistic humans is really tough. Can you speak to that? How to create ultra-realistic humans? You have an actor behind this to convey emotion, show the nuances and details of the faces, and maybe this is a good opportunity to also mention metahuman creator, that's part of Unreal Engine. Yeah, that's right. Humans are, by far, the hardest part of computer graphics because millions of years of evolution have given us dedicated brain systems to detect patterns in faces and infer emotions and intent because cavemen had to, when they see a stranger determine whether they were likely friendly or they might be trying to kill them.

We spoke a bit about Nanai, so the magic behind the virtual eye geometry system, but can you speak a little bit to Lumen and in general what it takes to dynamically light in all the complicated ways, the faces, the scenes that we discussed. What are some interesting things to you that made the magic of it happen? Lumen is a system for global illumination, meaning it's supposed to calculate the interaction of light with the entire scene in a way that mimics reality. The first generation of engines that did lighting just said, "Well, the light casts light and the surfaces it hits are lit and the surfaces it doesn't directly hit are dark, and that's just all the techniques we have." You'd have an area that wasn't hit by any light being completely black.

Outside of video games, a lot of people are using Unreal Engine for movies, for films, and big congrats. I saw War is Over, a short film that was made with Unreal Engine, won an Oscar. You can add that to the resume. That's huge, an Oscar-winning film made with Unreal Engine. What do you see as the future of the use of Unreal Engine in creating stories in the film industry? Increasing capabilities and productivity. The limiting factor in every one of these businesses is cost, and the more the engine can make their jobs easier, the more power that brings them. One of the big revolutions we've seen in Hollywood is the moving away from doing computer graphics integration into a human scene with green screens to moving to these large LED wall panels where they're displaying real-time computer graphics powered by the Unreal Engine. That's a massive improvement in quality.

I think as in many cases, AI will just help improve the human systems by shining a mirror to ourselves. I have to apologize for the pothead question ahead of time, but you've been, let's talk about the metaverse broadly. You've been a big proponent of the idea of the metaverse. We'll talk more specifically what that means today, but we've been talking about simulating reality better and better and better. The pothead question is what does it take to simulate reality to the level we see around us today? How far away from that are we to simulate this ultra-realistic, immersive fun reality that earth is? What does it take? We're going to get shockingly close over the coming years, certainly less than 20 years. If you look at the progress, what areas where we have achieved total photorealism and what areas where we fall short, we're getting very close in all non-human interactions you see in the world walking through a jungle or a city, all the lighting, it's very close, and that might be just a few years away. But then all of the problems that involve humans, human dialogue and intent have a much, much, much higher bar that they need to meet to satisfy our brains and convince us that they're realistic or real. I think that's going to be the primary challenge of graphics development and simulation development over the coming decade.

So you spoken, like I mentioned about the metaverse for many years. Let's step back. What is the metaverse? And speaking of fun, Fortnite, just hundreds of millions of people just enjoying themselves in this huge scale social game. You could call it a metaverse. Maybe you can describe the different flavors, the layers of how you see what the metaverse is. The metaverse is an idea who stock price goes up and down depending on who says what on what day, and some have an ability to drive it way down by opening their mouths, but ultimately this is about multiplayer social gaming experiences, you and your friends getting together in a 3D world and having fun together in any way you want. If you're playing Fortnite Battle Royale, in my view, that is capturing the essence of the metaverse, and it's especially in Fortnite when we got Sony on board so that all players on all platforms in Fortnite could play together, could voice chat together, and could be part of a single game experience, it really took on a new nature, which was not just like a multiplayer game with Heritage from Doom, but also a true social experience between you and your friends. And Fortnite Battle Royale is just one manifestation of that. Another one is Rec Room: VR, where you're standing around in VR with friends playing billiards and or shooting hoops or doing other light entertainment things.

Yeah, I would love to sort of talk about different aspects of that a little bit more because Epic has created a lot of amazing games, Unreal Tournament, Gears of War, but the game that I think is fair to say that transformed the gaming industry was Fortnite, Fortnite Battle Royale especially. Can you explain the origin story of Fortnite? Well, Fortnite has humble beginnings. In 2011, we just been in the final days of finishing one of the Gears of War games, and we wanted to explore ideas for new games, and we'd had a general idea that we would like to build some smaller games, online games and or to learn more about yeah, that space and not just have one single massive game in production at all times and only one. And so everybody in the company was given a week to form a team and work with whichever co-workers they wanted and build a game using Unreal Engine so you can actually build something pretty interesting in a week. And one of the teams built the very first version of what became Fortnite. The very first version of it had a different art style, but it had the idea at the core that you're going to build forts by day using this building system. Then night would come and you'd defend the forts against zombies, and the longer you could go, the more elaborate forts you could build and the more survival waves you could withstand, and it would get cooler and cooler with time.

Can you actually speak to the technical challenge of going from mostly a not online large scale gaming platform to being able to support with Battle Royale, a huge number of people playing with each other at the same exact time. What's the technical, four weeks. What's the technical challenges there that had to be overcome? Since 2012, we've been building online backend system to support player accounts and log in and all of the different systems there needed to make a multiplayer game. And we'd been building them to be scalable, and by some miracle, we built them stably enough that they were able to scale up. And so the online team who was responsible for patching that code, spent a year of intense work getting it to scale from 40,000 concurrent users to 15 million concurrent users.

Yeah, I think so. You don't need an alternate currency system. Unfortunately, a bunch of ideas have been conflated because people are trying to hype up different things. But this idea of large-scale multiplayer social gaming, that notion of the metaverse, there's 600 to 800 million people playing that kind of game every month. So you know that's real and that's happening and it's very much underway. VR has a much smaller audience. I don't think you need VR to have anything like this. VR is hardware that may or may not enhance the experience for some usage cases. For some it will probably be better and for some it will probably be worse, but certainly there's not any set of Battle Royale players flocking to VR. And the other thing is NFT is trying to equate digital or cryptocurrency to the metaverse. It's like, well, it's just a way of denoting money or value exchange. You can do that with money or you can do it with NFTs or whatever, but there's nothing about this future digital economy that fundamentally requires cryptocurrency or whatever. What you need is interoperability. Interoperability can happen through a blockchain, it can happen through a database, it can happen through standards bodies with defining standards and protocols. And we've been doing it for hundreds of years since the railroads were standardized. And it's not something that totally requires a novel technological solution.

Yeah, I mean, even on the topic of cryptocurrency, it's very frustrating. Blockchain and crypto is a really powerful technology that I think can enable a lot of the things that we're talking about, but so many people use it to try to make money to create these bubbles and the hype and the meme coins and the so on and so forth that becomes much less about, that drifts far away and rapidly from things that are actually of value, which is the experience of playing Fortnite and how you look when you play Battle Royale. I mean, it sounds ridiculous to say, but it's true. But that's valuable. That's like you have gold in the physical space. We know that holds value. How your outfit looks like in Fortnite, that as you're saying, provably holds value. And so you want to connect like a standard definition of money value to that and not let it become this hype thing, which NFTs that you mentioned are just become that. It quickly drifts away into the land of people trying to buy and sell and trying to make money versus staying close to the thing that people actually value. Forget the money. It's more about exchanging valuable experiences or things of value. So you can play Fortnite and then go to another video game and continue the valuable experience and then come back to Fortnite and do that kind of thing. So you're saying there might be a way to do that to basically create standards the way the web has different standards for displaying websites and all this kind of stuff, or the communication that's required on the networking side. So all the different standards that make the web work, there need to be those kinds of standards. What would those standards look like to enable the metaverse?

So first of all, that's a super exciting future where it's not hundreds or thousands, it's millions of creators that can just create different, small, or big elements of a world as big as earth. Just if you sort of close your eyes and imagine that world, that's really exciting, where it's not a centralized company controlling the release of a particular island or so on, it's people constantly dynamically modifying all the islands of reality in this digital world. So if you could speak to some of the technologies that can enable that. You mentioned the Verse programming language. First of all, also, how legit is it for you, CEO of Epic Games to be a co-author? The programming language theorists are losing their mind. So a co-author on a paper that's describing some of the nuanced details of a programming language. So maybe you could speak to this programming language called Verse. It's a functional logic language. What are some cool features of Verse?

Maybe can you talk about concurrency? What is it about Verse that allows for concurrency at the scale that you need? This is the one biggest technical problem that we're working to solve in this generation, and that is taming concurrency so that any ordinary programmer can achieve it by just writing ordinary code.

So what's the state of things with Verse? And I guess what you're outlining is if, and hopefully it is successful, this will be a big part of Unreal Engine 6. So what's the timeline? Where do we stand today? Well, there's a lot going on in parallel. The key thing with Verse is that we have been specifying what we think is the ultimate version of the language with all of the features we want, whereas we've been shipping more modest versions of language over time, and we've released dozens of updates to it over the past year and a half.

Yeah, by the way, Matthew Ball has been really helpful. He's a great... He wrote a really great book that I recommend people check out. There's an updated version. Let me just ask for because, again, there's a bunch of indie developers listening to this. I saw that a lot of solo developers out there that are using Unreal Engine, that they're basically creating video games solo. I saw... can highly recommend. It's great. Choo-Choo Charles. It's a great video game. Gavin Eisenbeisz, he... a great guy. He solo created this game that's, I think, quite popular. I believe he says he used visuals. He didn't even use C++, he used visual scripting. He used blueprints-

So we should talk about the fact that, amongst many other things, you've been philosophically and spiritually battling monopolies in general, one of which is sort of the Apple marketplace that charges 30% from developers. Can you speak about this, this idea that you believe that Apple and other companies, Valve, should not be charging that kind of revenue cut? Sure. Well, let's start from a very basic principle of computing. The first computer I owned was an Apple II Plus designed by Steve Wozniak and marketed by Apple, and then an IBM PC. And in those days, anybody could write code. Your computer literally turned on with a programming language prompt in front of you. You had to actually do work to not write a program and to instead run somebody else's program. That was incredibly empowering. And anybody could write a program, and anybody could put it on a floppy disk.

Well, I hope Epic and Apple find a path forward together and flourishing together, and Apple embraces competition better. One of the things I admire about this conversation that you mentioned, Steam a bunch, with kind word supportive and basically never mentioned Epic Game Store. I love that. So I really love that. It really embodies the fact that you want variety, you want freedom for people to choose the best thing, and, in so doing, create this large network of humans interacting freely with each other. Okay. That said, one of the competitive pressures that Epic has created a few years ago was by launching the Epic Game Store. And instead of Steam's 30% revenue cut, you went with 12% revenue cut creating the competitive pressure saying, "Listen, this shouldn't be that high of a cut," which I thought was amazing. This is a brilliant idea, and I think it still is a brilliant idea. It's wonderful. Now, in preparing for this conversation, I looked on the internet, and I saw there's a lot of criticism of EGS, Epic Game Store. First of all, I should say, the internet is full of drama and criticism. There's not enough celebrating of awesome shit.

Okay. What do you think is the future of the gaming industry? So well you've said to me a bunch of exciting stuff about indie developers, so do, what are called AAA video game companies, so these big gaming companies, do they have a future? What is their role? How do you see in the next five, 10, 20 years the evolution of these big companies and indie developers? Yeah, there's one constant in gaming that I think the industry manages to lose sight of from time to time astonishingly, and that's fun. And people play games for fun.

Okay, this is going to be a ridiculous question, but aside from the games you've created, what are some of the greatest video games ever created to you? What video games have been either impactful to you in your life or maybe you've seen created and you're like, "Huh, that's a beautiful art piece." It could be in a totally different realm. Obviously for me, I return often to the single-player domain of role-playing games of the Elder Scrolls series Skyrim. That was like a world that they created, a recent game, Baldur's Gate 3, that was a really incredible piece of work and art and doing a lot of innovative stuff, again in the single-player domain. Is there games like that outside the ones you've created? I'm most impressed with the games that have created what appears to be a full living, breathing world. Games that give you the sense that you're just a part of it and there's a lot more happening and there's always more. And it gives you the sense that you could go anywhere and do anything. Even though these games really do have finite limitations and there are places you can't go, really creating that sense of wonder is just a magical thing. Like Zelda: Breath of the Wild.

I love online gaming culture. I have to ask you because it's kind of like one of the legendary games is Grand Theft Auto. Speaking of the worlds that are just like... I mean, that's its own thing, right? That's that world, the characters, the style, the edginess, all of that. But the interesting thing about Grand Theft Auto VI to me that I want to ask you about is they took forever. It's the six-month thing that you mentioned before. There's some games like that just take years to bring to the conclusion. What can you say about that process that you eventually were able to take unreal to completion? If you were to look from the outside, why does it take Grand Theft Auto that long or other companies to take the games to conclusion? And what I mean, just insight into what that process is like. Making games is very hard, and especially when you're pushing the boundaries of something. With Grand Theft Auto, it's just the realism and feeling that you're in this huge city and that anything can happen and it's all living and breathing and you're just a part of it. The level with which Rockstar has brought quality to that genre is astonishing. And when you're building something at a level of quality and detail that's never been achieved before, you can't predict how long it will take. Whatever problems you're solving today to get to the next iteration of quality on it, you don't know what new problems that will unlock. And often you fix one thing and make it super realistic, and that just highlights the unrealism of other things that you then need to fix.

Let me ask you a big philosophical question. So you've created these gigantic worlds that bring so much fun to humanity, but you also get to learn about humanity. What gives you hope about us humans, about the future of humans, about the future of humanity? I see two contrasting worlds that have been brought about in the digital age. One is the world of social networks and people typing at each other and just massive negativity and politics and hucksterism and creation by engagement often promoting negativity and toxicity. That's a harsh world that I think is a step backwards in many ways. I think that the foundation of the world is actually a little bit shaky because of just the social dynamic that those platforms have brought on. But then I compare that with the good spiritedness of what's happening online when you're connected to real people. Actually playing Fortnite, playing Fortnite fill squads with people you've never met before and never talked to, and just judging what human connections develop there and whether they're positive, I found those to be really, really excellent and endearing.