Slay the Spire 2 patch fixes RNG bug after a fan's '8 hour descent into madness' proves it exists—alongside heaps of other updates and a new Act 3 boss

Slay the Spire 2 just released a major balance patch—and aside from forcing me into an update for my Silent Ascension 10 guide in the near future—it's delivered a whole heap of changes to the game, including one fascinating RNG bugfix discovered at the hands of a determined player.

RNG can always be a nightmare to figure out, mostly because human brains just don't perceive games of chance all that well. If you've ever missed on a 99% chance shot in XCOM, you know this feeling—a 1 in 100 chance is unlikely, but not impossible. And yet your brain tells you that some great and unforeseen injustice has visited you if it happens.

Anyway, one player spent about eight hours trying to prove they weren't crazy. User tckmn on the subreddit released a manifesto that's credited in the patch notes, an "eight-hour descent into madness", without which "we wouldn't have caught the issue."

The problem in question relates to Neow's Bones, a starting option that allows players to take on two starting relics in exchange for a curse—which could either be a non-event, giving you a curse that's just a dead card. Or you could get something like Debt, which could utterly spoil the economy of your run.

Turns out, you could tell if certain runs were more likely to give you Debt than others—specifically, if you started in the Underdocks, Neow's Curse was 54% likely to give you the Debt curse.

As the devs themselves explain it: "Most games, including STS2, use pseudo-random number generators (PRNGs). A PRNG is fed a seed value, and given the same seed value, a PRNG will always generate the same sequence of random numbers.

"Since we fed different seeds to each PRNG, we expected their results to be completely unrelated. But we were wrong, and it turns out that our strategy allowed players to predict outcomes given knowledge of unrelated parts of the game."

The issue was that the decimals which governed which Act 1 you got also happened to correlate to your Neow's Bones curse: "For example, if our act roll is >0.5 (we’re in the Underdocks), then it’s highly likely that our Neow’s Bones curse roll will be