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Lex Fridman Podcast · 5 min · Apr 30, 2025

ZZT grew from a text editor through player testing

Tim Sweeney turned a text editor into ZZT, tested it with neighbors, then released one game free and sold two sequels. The process shows how a small experiment found users and began funding Epic.

Tim Sweeney

Tim Sweeney is founder and CEO of Epic Games.

Created Unreal Engine and co-created Fortnite, and has led Epic Games since founding it in 1991.

  • Lex Fridman, Host · Host, Lex Fridman Podcast

    Robotics and AI researcher at MIT; started the show in 2018.

About this segment

Tim Sweeney turned a text editor into ZZT, tested it with neighbors, then released one game free and sold two sequels. The process shows how a small experiment found users and began funding Epic.

From “Tim Sweeney: Fortnite, Unreal Engine, and the Future of Gaming | Lex Fridman Podcast #467”, Apr 30, 2025. Watch the full episode

“I took notes about what they got stuck on and what they enjoyed and where they felt bored and just iteratively polished the game until I felt it was good.”
Tim Sweeneyat 19:34 · Lex Fridman Podcast19:34

Takeaways

  1. ZZT started as a text editor Sweeney found boring.
  2. He watched players and polished the game based on what they did.
  3. A free first game helped sell the two sequels.

In this episode

Full episode
  1. 29:53Indies have a better shot by avoiding crowded genres4:12
  2. 2:32:51Fortnite shares shop revenue with creators based on engagement5:36
  3. 3:28:41Apple's app fees suppress software competition6:21
  4. 2:26:45Fortnite's backend took a year to scale to 15 million users3:47
  5. 1:55:10Game engines can supply context AI video lacks7:00
  6. 4:06:08Social games are concentrating playtime and investment6:16
  7. 17:22ZZT grew from a text editor through player testing4:33

  8. 3:13:28Verse aims to make concurrency invisible to game programmers7:46Up next

Transcript

Transcribed by machine (Whisper) from the episode’s audio, so a word may be off here and there.

  1. 17:28

    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 just moved from an Apple II. So my brother bought my family an Apple II right after I'd visited them in California. So I've been programming on that for a few years, learned a lot of techniques, but there weren't many Apple II users around still by the time that cycle came to an end. So I'd just gotten an IBM PC of my own. I was learning to program, and I realized I needed a text editor. So I started writing a text editor. You know, 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 had finished it up, and I was like,

  2. 18:15

    well, okay, I have a text editor, but this is pretty boring. And so I made the cursor into a smiley face character, and I had the different characters you could place in this document perform different gameplay actions. Some would be walls, and some would kill you, and some would be moving objects that could fly around the screen. And so this text editor I made evolved into a little game editor, so I was building these levels for a game. I put a lot of time into building an editor in a primitive set of objects, about 20 or 30 different objects, It's enough to build a really cool and compelling game, but not so many that players would lose track of what they're seeing.

  3. 18:50

    I started off just building different game levels. You know, the idea is you'd be on a series of boards. They'd be connected by, you know, going north, past the end of the current board would take you to a new one if it was open, or maybe it was blocked, and you couldn't go there. I built this whole game world around that, and, you know, this was the game that became ZZT. And I was having fun with it, building it and playing it, but I didn't know if it would really work.

  4. 19:12

    I did this experiment. I started inviting neighbors over, like some adults, some kids of all different ages, and sat them down from it and said, here's a game I made. Figure it out. And I had to force myself not to tell them what they need to do, right? Because I really wanted to learn if they were able to discover it all for themselves. Today we would call this a user experience test, and there's a whole field of research around user experience research, but back then it was just inviting some kids over to play the game.

  5. 19:41

    I took notes about what they got stuck on and what they enjoyed and where they felt bored and just iteratively polished the game until I felt it was good. And I put it out and released it on, well, this was before the internet, so there were bulletin boards. I uploaded it to a bunch of local bulletin boards. And from there, it started spreading because the way to build up cred for bulletin board users was to upload new files and to claim that, hey, I was the first that brought this to you.

  6. 20:05

    And so there was a natural tendency of the software to spread. I decided to use the shareware model. So I didn't just build this one game. I built a trilogy of three games. I released the first one for free. And I said, hey, if you'd like this, buy the two sequels. And I included my parents' mailing address and said, you know, send us $30 and you can get the sequels to this game. And the check started coming in within a few days.

  7. 20:31

    I was making like getting three or four orders a day. I was making like $100 a day. I'm like, woo, I'm rich. because, you know, being a 20-year-old, that was, like, a pretty big deal. What did that feel like, just getting money and probably feeling this immense success from something you've created? Well, you know, I looked at money always just as a tool to help you fund accomplishing cool things.

  8. 20:56

    And, you know, having enough to do the things you want to do is the critical thing. It's always been just very utilitarian. But the knowledge that other people all around the country And then, you know, a month later, all around the world were playing the game. That was mind-boggling. You know, that me, like this little kid who'd put out a game on a local bulletin board, could be doing international business and chipping disks all over the world to players because the software was spreading on its own.

  9. 21:23

    It was just magical. And that was a new thing for software. That did not happen with mechanical devices. You manufactured one, you sold it to somebody, and they had it, and that was it. But software could spread. That was just really cool to see, and it made me realize there's really no upward limit on the potential for a business like that. You know, we saw Microsoft as a big juggernaut company at the time, but I was like, hey, you know, if Epic does games good enough, you know, we could accomplish what they've accomplished with operating systems.

  10. 21:50

    And the sky was the limit.