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  • Hacker News
  • The post suggests replacing the linear congruential generator (LCG) with a permuted congruential generator (PCG). The latter has more random-looking output.

    Another solution is to switch to a cryptographic hash function. For example, using sha256(seed || event type || counter) only requires storing seeds and counters in the save game.

    This has several benefits:

      - You can find efficient implementations on all platforms without having to roll your own.
  - Gives the same output on all platforms by design.
  - Output is practically indistinguishable from randomness by design.
    The main downside is that sha256 is significantly slower than any non-cryptographic PRNG, but considering how few random numbers you need during a typical game, this doesn't really matter.
    by sltkr
  • > (By the way, floor 2 Corpse Slugs will both be attacking on turn 1 less than 3% of the time. How nice of them!)

    I assumed that was just deterministic. Didn't realize the game permitted such a challenge on floor 2 :(

    by darepublic
  • This is such a great article- I’ve had so many runs where it’s felt like “why am I always getting this random card?” And now I’ll know! Thank you!
    by FromTheFirstIn
  • This is also the cause of the thing in Minecraft where you find surface clay, move X blocks over, and dig straight down into diamonds.
    by iliveinberlin
  • Interestingly, StS2 got this problem because it was using C# System.Random in Godot, while the RNG class in GDScript (Godot Engine's own scripting language) is using PCG32 which should be free of this particular problem.
    by stdc105
  • I haven't had time to read the whole article, but I really appreciate the cross section of the world that reads HackerNews and plays STS2. STS1 and STS2 are my favorite games and to see this pop up here brought a big smile on my face. Thanks for sharing.
    by kami23
  • Combining this article and discovery of an unwinnable seed in the original Slay the Spire [0] — I've always pondered the existence of some kind of "RNG hell", where a game uses the time as its random seed and, due to some quirk of the hashing function and the game mechanics, the game is rendered completely unwinnable for (say) four days straight. (Sometimes it feels like I'm in it!)

    [0] https://oohbleh.github.io/losing-seed/

    by jcalx
  • > Implementing a PRNG within the codebase instead of calling the C# standard library has an additional advantage: seeds are guaranteed to be the same on all platforms. In Spire 1, seeds on the desktop version of the game were different from seeds on the mobile version of the game, because the standard library implementation of PRNG differed between platforms. It is also worth mentioning that the standard library implementation might change over time, which would break all past seeds.

    This is the correct conclusion - game developers should consider gameplay-relevant random generators part of their gameplay code rather than platform code.

    by account42

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