What would it take to modify a Nintendo Switch cartridge game?

The realistic answer is that you would usually need access to the original source code or spend years recreating the game through reverse engineering. Depending on the title, you might also have to deal with obfuscated code, ahead-of-time compilation, encrypted assets, custom data formats, and runtime protections. Creating a new game inspired by the original—or starting with a more accessible PC modding project—is far more practical.

The programming language is probably the least difficult part. You’d need strong experience with C/C++, assembly, reverse engineering, console hardware, and game development. A sensible learning path would be to start with PC game modding or build a small game in an engine that supports Switch development, then learn the platform-specific tools and APIs through legitimate development hardware and documentation. Modifying an existing cartridge would be a much harder reverse-engineering project on top of that.

Commercial Switch games are protected by several layers: encrypted software, authentication and signing requirements, proprietary formats, and anti-tamper mechanisms. You would generally need to analyze compiled binaries without the original source code, understand the target processor and libraries, modify the code or assets, and produce something the console will accept. Even getting a clean, useful decompilation is difficult because names, structure, and high-level logic are usually gone.

The physical cartridges are effectively read-only from a normal user's perspective. They aren’t like rewritable development media, and their storage technology and security checks make directly editing one impractical. In theory, someone could manufacture replacement hardware or create a new cartridge-like device, but that introduces major hardware, authentication, and manufacturing problems.