How Did Rogue Generate Its Random Dungeons?

(howtomakeanrpg.com)

27 points | by danschuller 22 hours ago

4 comments

  • throwlifeaway 14 hours ago
    Once every few years I find myself dumping many many hours into Nethack (the open source successor to rogue). Never once have I beaten it, despite playing usually with several tabs open to various wikis and guides. Eventually I die while on a super long run (by my standards) and totally give up in frustration, beginning the next several-year dormant period until the next time I play.

    To any game developer planning to call their game with random upgrades a "rogueli[tk]e": play Nethack. Your favorite roguelike was almost certainly created by someone who did.

    • chuckadams 1 hour ago
      I'm thinking of making a mobile game that's a clicker or something completely not roguelike, naming it "Roguelike Roguelike", and ensuring that the word "roguelike" appears in every sentence of the description. I'll make tens.
  • hosel 13 hours ago
    I never got into Rogue, though I did love Nethack. If you’re into these actual rogue-likes, I picked up Caves of Qud recently, highly recommend.
    • red-iron-pine 6 minutes ago
      won a Hugo Award recently IIRC.

      fun game. Book of the New Sun meets Nethack meets Gamma World.

  • genpfault 17 hours ago
  • avadodin 16 hours ago
    I missed a definition for "random".

    Did it have a specific PRNG and seed?

    Was it platform–dependent?

    • McGlockenshire 11 hours ago
      Literally the second line of the article addresses your questions by linking to the source code repo under discussion. Every single one of the sidebars about the topics being discussed links directly to the relevant code.

      The article even tells you it's C. The copyright dates on the code are 1980ish. It's talking about rogue, not rogue.exe, so this is going to be on Unix, real Unix. So, it'll be using rand(), the bad one, surely, just by what it is and where it is. That completely answers all your questions.

      All you had to do was click links.

      edit2: lmao okay so I read the code myself and you'll never, ever guess what it does. It does NOT use rand().

      • suprjami 8 hours ago
        Spoiler: Rogue just implements its own Linear Congruential Generator.

            #define RN (((seed = seed*11109+13849) & 0x7fff) >> 1)
        
        I've poked around in a couple of libraries from this time. At least QuickBasic and QuickC also implemented an LCG (not the same one either). So a 1980s PRNG from Microsoft just gave you an LCG with different constants.

        I would not be surprised if other contemporaries like glibc, Borland, Watcom, Lattice, etc all did the same. Or did they do something else/better?

        • avadodin 6 hours ago
          Thank you.

          I think the algorithm used and the seeding method are very relevant in procedurally generated games like Rogue, Elite and Minecraft so I was disappointed when the author just used Random().

          And yes I could have read the code or remembered a previous time whence I might have learnt the same bit of information but instead I read the article.