Hacking Potential Anti-Piracy Mechanism in AC:NH

NekoMichi

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tl;dr version:
If you're using an illegitimate copy of ACNH, the game may alter its RNG to make rarer fish impossible to obtain.
This was based on catching 100 fish by visiting an island on an illegit copy and seeing how many were rare fish, then trying to do the same by visiting an island from a legit copy. The "visitor" was from a legit copy of the game.

The long story, along with raw numbers:
Summary
By visiting islands in both legitimate and illegitimate copies of Animal Crossing: New Horizons and examining the spawn rates of fish, a discrepancy was found in the distribution of rarity tiers of fish that may indicate a potential anti-piracy mechanism within the game. While spawn rates appeared normal within the legitimate copy, only lower-tier fish would spawn on the illegitimate copy's island. No "rare" fish or above were caught within a sample size of 100.

Method
Three Switch systems were set up to test different scenarios.

Console A
2017 original Switch running firmware 10.0.1 and Atmosphère 0.11.1
Illegitimate copy of Animal Crossing: New Horizons installed via nsp file with update 1.2.0
Acted as host island

Console B
2017 original Switch running firmware 10.0.1 and Atmosphère 0.11.1
Legitimate copy of Animal Crossing: New Horizons purchased from the eShop with update 1.2.0
Acted as host island

Console C
Unmodified Switch Lite running firmware 10.0.1 and no CFW
Legitimate copy of Animal Crossing: New Horizons purchased from the eShop with update 1.2.0
Acted as visitor to the host islands

Cheat engines such as EdiZon or any other external means of manipulating spawn rates were not used at any point during the tests.

The first test was opening up the island on console A and then visiting it via local multiplayer from console C. I positioned the player character on the pier of the beach on the island and used fishing bait to spawn fish and recorded each species of fish caught. This was repeated until either a "rare" tier or above fish was caught, or 100 fish had been caught with no rare fish spawning.

The second test was opening up the island on console B and then visiting it via local multiplayer on console C. The same test was performed by positioning the player character on the pier and capturing fish until either a "rare" fish appeared or until 100 common fish had been caught in a row.

The rarity of fish was defined by the star-rating from an ACNH guide app.[1]

Results
When visiting the island on an illegitimate copy of the game, no rare fish spawned at all. Based on the spawn table for April in Southern hemisphere islands[2], the following fish were supposed to be available at the pier/sea area, and the numbers actually caught were as follows:

Screenshot 2020-04-30 at 03.43.27.png


All of the 100 fish caught on the island were of 1-star rarity and no "rare" or above fish were spawned at all. On the other hand, when I travelled to the island on console B, within 7 attempts I was able to catch an oarfish, which is a 3-star rarity fish. Going back to the island on console A, I tried catching fish in the river areas as well as bugs and found that only 1-star rarity creatures spawned. On island B, I tried again on random rivers as well as bugs and was able to find rarer species within less than 50 attempts. Detailed numbers aren't available for these as river fish and bugs were not originally part of the scope of this "experiment".

Other Notes
From these numbers, it seems that rare fish are either impossible to obtain or have abnormally low spawn rates on illegitimate copies of the game. The sample size of 100 might not be very large though and ideally there should be many more tests to confirm this. But based on these limitations it seems that "rare" sea fish have a less than 1% spawn rate on illegitimate games and is significantly different to that of legitimate copies. Also this was only tested on two different islands, while the main difference is the legitimacy of the games there is always the possibility that this is caused by another factor.

Sources
1. ACNH guide Android app by Gene Sy
2. Eurogamer April Fish List for Animal Crossing: New Horizons

Has anyone else tried anything like this before? I kinda lost the will to live after pulling up over 100 fish, recording the stats, and comparing between islands. I'd be interested to see if anyone else experimenting has also observed similar results. Bearing in mind that out of the 3 devices tested only device C is my own main device so there might be other factors involved on the other 2 consoles. However I wouldn't be surprised if Nintendo implemented something like this as an intentional way of trolling pirates.
 
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link42586

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I never got the egg day event or saw that bunny once and I was day one in the game. But I didn't update to 1.0.2 or whatever right away. Either way I should have gotten that event but it never showed and I load it up and grab all my fruit and fossils at least.
 
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Ushiara

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I was trying to catch rare fish when raining on my second switch (With CFW) with my first one (OFW). I caught around 100 fishes as well and never got any rare fish...
If it can help you

EDIT: It was raining two days later on my OFW switch and i was able to catch some rare fishes with around 40 tries
 
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DarknessPlay3r

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Just to add to the data, I've seen similar common fish numbers. However I have managed to catch quite a few (7+) Barred Knifejaws, 3 Coelacanth, and a few Oarfish. With a rather limited amount of fishing.

My partner has seen better numbers though she plays a lot more then I do. Looking at whats been in and is currently in season she has caught a lot of what's available.

We're using a Northern Hemisphere setting. Along with Atmosphere, and the most current AC:NH updates.
 

jurai

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I never got the egg day event or saw that bunny once and I was day one in the game. But I didn't update to 1.0.2 or whatever right away. Either way I should have gotten that event but it never showed and I load it up and grab all my fruit and fossils at least.

were you doing regular online play, as I recall there were manual steps involved if you were offline beyond just doing a patch install
 

Alree

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Nope.
Every Spawn rate, of every aspect of this game is currently stored in CSV like files. and fixed.

There is just a lot of RNG in game. And Induced by a specific Seed every day.
In fact every day, you have a different RNG Seed, different in every console


every aspect have already been datamined/decompiled.
We do have the same game.(Piracy and genuine copy are same)

1st, just DUMP your legitimate copy and compare with a Internet dumped one.
Also, it's already confirmed that Game send many data to Nintendo servers. Time played, ore gathered, how many times, steps, etc..
in other way, when you go online (not Lan Play) there is plenty of "check" between your game and Nintendo Server

A sample of 100 is a tiny sample.
https://en.wikipedia.org/wiki/Law_of_large_numbers

400px-Lawoflargenumbers.svg.png
 
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NekoMichi

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You're right, 100 is absolutely not enough to determine anything. I'll be doing more tests on different days to check if it's just weird RNG/seeds or if something's actually going on. The thing is, I've visited on 2 other days and only found common fish too, just I didn't properly document them. Either way, if I can get a larger sample size and find anything unusual, I'll report back. It just seems really strange for this to happen over 100 consecutive times, then repeat over 3 different days.
 

Alree

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You're right, 100 is absolutely not enough to determine anything. I'll be doing more tests on different days to check if it's just weird RNG/seeds or if something's actually going on. The thing is, I've visited on 2 other days and only found common fish too, just I didn't properly document them. Either way, if I can get a larger sample size and find anything unusual, I'll report back. It just seems really strange for this to happen over 100 consecutive times, then repeat over 3 different days.
Do your test in Lan Play without any Internet connection.
Hour, Meteo, Season, Internal Switch Seeds etc.. change the way Fish Spawn.
Also all switch may not be exactly at same hour. even with NTP On
 

NekoMichi

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Do your test in Lan Play without any Internet connection.
Hour, Meteo, Season, Internal Switch Seeds etc.. change the way Fish Spawn.
Also all switch may not be exactly at same hour. even with NTP On
Oh another thing I forgot to mention, the Switch with the illegitimate copy apparently hasn't been connected to the Internet since 10.0.1's release and the game was installed (along with the update) completely offline. The console hasn't connected to the Internet with the game before. I'm not sure if this makes any difference though.
 

Alree

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Oh another thing I forgot to mention, the Switch with the illegitimate copy apparently hasn't been connected to the Internet since 10.0.1's release and the game was installed (along with the update) completely offline. The console hasn't connected to the Internet with the game before. I'm not sure if this makes any difference though.
Time, change everything.
Random generator always use Computer Local Time.
Dunno if this one use JoyCon Accelerometer
 
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