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If it goes from 0 to 65535, and you're looking for 00000,11111..55555, that would be 6/65536 or just under 1 in 10000.
I wasn't counting 66666, but I counted 00000 - is that one possible?
This is especially lucky in FireRed, LeafGreen, or Emerald, as you can't manipulate your ID in those (unless you run a script to keep loading a state before you confirm your name).
If it goes from 0 to 65535, and you're looking for 00000,11111..55555, that would be 6/65536 or just under 1 in 10000.
Yep, I've gotten 00000 before, so it's 6/65536. This is especially lucky in FireRed, LeafGreen, or Emerald, as you can't manipulate your ID in those (unless you run a script to keep loading a state before you confirm your name).
In FireRed, LeafGreen, and live battery Ruby and Sapphire, there's an unpredictable algorithm run on startup that determines the starting value, which means you're screwed for RNGing on a physical copy of those.
So yeah, a vanity ID on a physical copy of one of these games…kind of a big deal. ;D
And yeah, Gen I ID abuse is fairly easy but also very limited with how much you can reliably get. It's a must for any sort of glitched run, though, because that value factors into ACE. It's the reason the rules have become so much more strict ever since those games' RNG was cracked; prior to its discovery, nothing emulated it properly, and now there's just one emulator that does, plus all the values Isso mentioned that one has to take into account.
I guess it's my turn for a "Chickasaurus moment" because I want to hammer down how lucky this is and need to calm down anyway.
The GBA has an internal timer that increments by 1 every CPU cycle, which is about 59.59 nanoseconds or 16.8 million (2^24) increments per second. Most games don't bother to use this, and instead opt to time things by incrementing by 1 every time the screen is refreshed (VBlank), which is about 60 times per second or one frame. In Gen III, these frames are the exact same "frames" used in players' RNG calculations. This is because nearly every RNG operation done by the game is done using the current value in memory that changes every frame through a linear congruential algorithm (multiply by some set number then add some set number,) a very primitive way of creating "random" numbers (not that they ever expected anyone to bother to figure it out). This value (the seed) starts at 0 in Emerald, and 5A0 in Ruby or Sapphire with a dead battery. In FireRed, LeafGreen, and live battery Ruby and Sapphire, there's an unpredictable algorithm run on startup that determines the starting value, which means you're screwed for RNGing on a physical copy of those. The LCG is arguably less "primitive" in that it ends up allowing every possible 32-bit value to occupy that memory location, still less than the amount of possible IV/nature combinations, but enough that most wouldn't care. 524288 of these values (2^32 / 8192) result in shiny Pokémon, as that many return "true" when put through an algorithm using both your ID and secret ID as variables (simplifying a lot here, but it's not the main focus anyway.)
So we have frames, and we have the GBA's internal timer. The 60 Hz timer for RNG was mostly retired in Gen IV (initial seed generation aside), was completely nonexistent in Gen V unless you were in the Entralink, has an unknown function in Gen VI, and finally returned in Gen VII. In Gen III, it still determined everything, except for one thing…IDs in FireRed, LeafGreen, and Emerald. These used the 16.8 MHz timer, which I'm guessing VBA stumbles with now and then, making these nice save files technically legal hacks:
[img]https://i.imgur.com/GYI3lDk.png[/img]
[img]https://i.imgur.com/jqZ4LjY.png[/img]
(had to bite the bullet with VBA in order to run the script I mentioned a few posts above)
Odder yet, the secret ID is generated by using the value that changes with every increment on the 60 Hz timer! Odder again, the value in question is rewritten when the normal ID is generated, making these also impossible to manipulate without an emulator! I can't come up with any explanation for this other than:
[img]https://i.imgur.com/Im4xlB7.png[/img]
So yeah, a vanity ID on a physical copy of one of these games…kind of a big deal. ;D
[size=8pt](In Ruby and Sapphire, the ID is determined from the upper 16 bits of the seed at the end of the Birch intro, and then the LCG is incremented by 2 and the upper 16 bits of that are used to determine the secret ID. So in those, you can't get the shiny IVs you want with just any visible ID, because it's tied directly to the secret one.)[/size]
And yeah, Gen I ID abuse is fairly easy but also very limited with how much you can reliably get. It's a must for any sort of glitched run, though, because that value factors into ACE. It's the reason the rules have become so much more strict ever since those games' RNG was cracked; prior to its discovery, nothing emulated it properly, and now there's just one emulator that does, plus all the values Isso mentioned that one has to take into account.