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Comment by mindstab | Hacker News Reader

Not necessarily. If it simply sets the random seed once as the program starts, then saving the state of the game, and reloading it repeatedly will give the same result from rand(), because the seed hasn't changed and you are rewinding/repeating time.

If I flip a coin in a deterministic universe, it's still "random" (air flow, force exerted, etc), but if I "rewind time" and play it back, I'd get the same result.

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You missed the point. Part of the game is that you thought you could control the number with your timing of exactly when you hit the button (it shows the "die" spinning above your head, you hit a button to jump and hit the die, at which point it stops spinning).

Yeah but why should that matter? If you hit it at a random time and it should be random, then why does it matter if the random number is generated at that instant or before? It's all still random in the user's eyes.

Because it's not random in the user's eyes. We thought the number was totally based on our input; we would try so very hard to perfect our timing to get the numbers that we wanted.

The author is not the intended user; he is using an emulator. The dice roll seems random to the intended user's eyes.

So? He was the intended user when a younger version of himself played it on the actual console. Many players thought that their timing alone controlled the value. The author has simply used an emulator to show that that is false.

Well, the problem is, that's different to real dice. And subtlely different to the expectation of how it should work. If you throw a die, you could, with enough fine motor control, throw to get the number you desired. Or, in roulette, you could pick the right number the ball will land in by observing the speed with which the ball is spinning. In theory. Is there a practical difference? No. But, it still feels wrong that the game would work in a way that completely ignores the action of the player.

Predictability in roulette -

http://www.newscientist.com/article/mg21428644.500-roulette-...

Perhaps some people thought there was actually a non-random element, whereby hitting the button at a specific timing could cause a specific number to turn up.

It's like Press Your Luck: you could theoretically determine what value you get, but human reflexes are too slow to hit the value you want consistently, so you might as well play randomly for fun.

Unless you're Michael Larson, of course.

Or Chuck Norris

I don't see why it would even make sense to be able to control your die roll at all. I think the spinning was just an animation. This ain't slots.

That's the illusion though! Everyone playing the game thought it was slots!

A agree, from a game design standpoint, it doesn't make much sense to make it like slots; but that's the way it appears to the user.

The funny thing is, modern slot machines do the same thing. The spinning is just for show - a PRNG decides exactly where the wheels should stop.

I think the author is still confused:

> They took the time to display a spinning dice over Mario's head, so why couldn't they just add the random function that determines the dice roll AFTER the player head-butts the dice, and not before? Even though the dice roll IS random, the player cannot alter their fate while watching the dice spin above their head.

This reveals a misunderstanding of how the PRNG would work. Whether you compute the random number before or after is irrelevant, provided that nothing else asks the PRNG for output during that time.

What would change it is reseeding the PRNG based on the amount of time waited, or using the PRNG in displaying the animation. However, while this guarantees a causal effect, it doesn't really change the randomness in any measurable way (that is, to anybody playing the game as intended, not through an emulator) and so it would have no effect. So the designers made the right choice in my eyes.

What would change it is reseeding the PRNG based on the amount of time waited

The argument by the author is that the game implies that this occurs.

> If I flip a coin in a deterministic universe, it's still "random" (air flow, force exerted, etc), but if I "rewind time" and play it back, I'd get the same result.

Couldn't quantum mechanics mean this is not true?

What do you mean?

I view "rewind and play back" essentially as replaying the exact way the quantum states collapsed. Although quantum mechanics are probabilistic (whether you believe in multiverses, Copenhaguen, etc.), the key here is that you're replaying the same probabilistic results and not "throwing the dies" again.

Or maybe I misunderstood your point?

I'd also argue that this is Mario Party using a PRNG. QM do not apply!

My understanding would be quantum mechanics would not play the same if you went back in time. It is truly random.

But since time travel is impossible then maybe it makes no sense in general to talk about.

Plus as pointed out the OP does say it was a deterministic universe (but I would have thought that is not what we are in due to QM)

Even if it turns out we live in a non-deterministic universe due to QM, that obviously does not apply to a deterministic universe.

I don't think there are very many quantum effects working on coin tosses. It seems (to my relatively inexperienced eyes) like something handled pretty adequately by classical mechanics.

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