More than just that, procgen as a whole requires an entirely different level of vigilance to avoid nondeterminism creeping in if the game requires it to be reproducible. None of the inputs to the procgen algorithm can be allowed to even so much as brush up against code you aren't actively exerting complete control over, and care is required to avoid inadvertently encountering any platform specific hardware quirks.

> It is also worth mentioning that the standard library implementation might change over time, which would break all past seeds.

If the stdLib changes and you need to use the same, then you're unfortunately going to be suck with porting the previous version into your own library. It's pretty forward thinking from the devs here, I would love to see my boss' face if I told him we need time to port some of the stdLib incase they update it in the future.

I had to check for my own curiosity, but it looks like the Random class has not been updated in 12 or so years. At least in the inital subset of framework to core.

https://github.com/microsoft/referencesource/commits/main/ms...

Sometimes it is useful to deal with a platform where such things are not even available, never mind platform dependent. Then see how quickly your code breaks.

Standard library invocations - including random number generation - often break entirely when targeting wasm freestanding for instance, as in that case there is really very little "platform" to speak of.

The criteria for calling a RNG "cryptographically secure" are incompatible with the game design goals here.

The game needs a RNG that's stable when seeded, for reproducible runs. I look for the same kind of qualities when doing generative art.

In comparison, a CSPRNG should be safe from oracle attacks, which is essentially the opposite goal.

The motivation boils down to trying to make runs with the same starting seed feel "similar" in meaningful ways. It's "better" in a vibes way if both you and I were offered the same card choices in runs with the same seed, even if we took different amounts of turns on the first battle.

The main reason to allow users to set seeds manually is to allow players to share seeds among themselves. And the reason that players want to share seeds is because players will find exceptionally rare seeds that other players might want to try out. This sort of exceptional rarity might take the form "the first shop in act 1 sells a relic that gives you 2 potion slots, then the act 2 ancient offers a relic that gives you 4 potion slots, then the act 3 ancient offers a relic that fills all your potions slots at the start of every combat". However, when players share seeds, they aren't sharing the exact series of inputs they performed in that game. This means that the relics that have been "randomly" offered like the ones above need to be offered on the same seed regardless of any prior player decision. And player decisions can generally cause the RNG to advance an arbitrary number of times. So this means that you want to have entirely separate RNGs for every thing that the player has any power to influence, because this makes the randomness of a single seed more usefully reproducible in practice.