alt Hacker NewsCSPRNGs are absolutely seedable deterministic functions that will result in entirety reprodible runs.
The only difference is that if you don't know the seed it is computationally difficult to predict the next value given the previous ones. But that's not something any game dev is ever going to want to do (or waste time trying to do)
In contrast, OS CSPRNG APIs usually only provide access to a CSPRNG that the OS seeds on its own, in some way not fully controllable by the user. E.g. using fast key erasure & hashing in data from a hardware entropy pool.