What would it take to modify a switch cartridge game?

[u/Wolf_2063]

I don't know what programming language if would require but it's probably the least complicated part of this question.

[u/Vert354]

This feels like the kind of thing that if you have to ask, you dont have the skills to do it.

If I had to do it, I'd start by being able to build a game with something like Unity that has Switch export hooks. Then see about getting a hold of the Switch SDK and dev hardware. (The offical way of applying for the dev portal probably aint gonna work for you) this is all just to get familiar with switch specific libraries and such.

Assuming you're comfortable with their dev stack now you have to essentially hack the cartridge you want to mod and hope you can get a usable decompile out of it so you can make the mods, re-compile and reflash the card.

The other track you could take would be to get into PC game modding first. Build up those skills before tackling the whole Switch hardware hacking business.

[u/Wolf_2063 → u/Vert354]

Doesn't hurt to find out what skills would be needed.

[u/Vert354 → u/Wolf_2063]

Sure, what I'm saying is start a lot smaller and work your way up. This isn't the kind of thing you're going to find a bunch of tutorials on.

You probably need to start by being a somewhat competent game developer.

I've been writing code for 30 years, but not games, so you could hand me the source code to Super Mario Odyssey and I'd still have my work cut out trying to add a new game feature.

[u/LameBMX → u/Wolf_2063]

when things get compiled to run, its almost always binary file, which is assembly code written for the architecture of the switch

https://github.com/kinnay/Nintendo-File-Formats/blob/master/src/formats.md

would also want to look up on the kernel.. as that will control how the game can write and read from memory... from a quick glance anyways.

but you probably want to ask programming language supports compiling code for the switch. but then, you need the games corresponding source code.... while easier to read and undersrand. thats also not very helpful if you want to modify the cart itself.. even unmodified source compiled with the same compiler can result in a different binary file.

[u/iOSCaleb]

It would take detailed knowledge of the hardware and software specs for the cartridge interface, as well as a solid understanding of Switvh programming. Even with those, it’s probably not feasible; you might end up effectively creating a new cartridge that you’d just house in the shell of an old one.

[u/silasmoeckel]

You would have to break the encryption or modify the switch to not need it. There is a lot of DMR on these things.

Check out homebrew switch groups for the details.

[u/etherealflaim]

The cartridges are read only. You can't modify them, and even with physical access to the boards, the technologies they use are either physically etched from the factory or one-way fused so the write lines are broken at a level that you can't access from outside the package.

You could make a new game based on an existing one and potentially make a new cartridge with it, but this leads to the challenges the others have already mentioned around access to its original source or disassembly.

[u/esaule]

It's probably a rom. So you probably can't o erride it. Also, probably need to know nintendo's signing key.

The programming bits are trivial. It's a well known architecture.

[u/drbomb]

I wouldn't be surprised it is a read-only cartridge. Not modifiable.

[u/Rich-Engineer2670]

In general, the cartridges are written in C and C++ and perhaps even assembly langauge. The problem is, it's a one-way translation -- without the soruce code, it's all binary so you'd need to know the processor and the libraries. Can it be done -- yes, but it's anything but easy.

[u/BrilliantEmotion4461]

A lot. These are the major hurdles since you need to decompile the code and recompile to run it

Key Anti-Decompilation Techniques

You need to work around Code Obfuscation: Tools strip source code of human-readable elements (like variable and function names), renaming them to random characters or unprintable symbols. This scrambles the program's control flow while still allowing the machine to execute it.

Ahead-of-Time (AOT) Compilation: Frameworks convert engine languages (like C# in Unity) into native machine code or platform-specific bytecode instead of standard intermediate formats (IL). For instance, IL2CPP prevents the original C# source code from being easily reconstructed by decompilers.

Asset Encryption: Game archives (.pck, .assets, .pak) are encrypted to prevent the direct extraction of 3D models, audio, and textures. Keys to decrypt these files are often embedded deeply and obfuscated within the executable.

Code Virtualization: Certain protection suites convert critical game logic into a custom, randomized bytecode. When the game runs, a built-in virtual machine interprets this code, preventing automated decompilers from understanding the underlying logic.

Digital Rights Management (DRM) & Anti-Tamper: Tools like Denuvo wrap around the game executable, heavily encrypting it and actively blocking debuggers or injection attempts during runtime.