3dstool VS ILSpy

For open-source tools, Project CTR includes ctrtool to extract many 3DS formats including CIA, and makerom to build an NCCH, CIA, or CCI file. It's a bit old so I'm not positive it'll work exactly, but there's a guide on extracting a CIA using ctrtool and 3dstool, then rebuilding it using makerom and 3dstool.

You can rip the game to a cia file using GM9, and then on a PC use ctrtool and 3dstool to extract cia contents, extract the romfs from that, and then extract the romfs contents which will have all the game data files. I will warn you though that everything is in special Nintendo formats and it's different in some games. You may or may not be able to convert them to a normal PC audio format with various tools.

First, go grab this: https://github.com/icsharpcode/ILSpy. It's a decompiler that will break Rust down. Hope you like C#.

If its a C#/.NET exe you can use ILSpy to get the source code https://github.com/icsharpcode/ILSpy

Well, it might not be exactly what you're asking for, but ILSpy lets you choose what version of C# you wish to decompile an assembly to. This is great for learning how a specific feature used to be coded in C# prior to some new syntax/compiler feature being added.

You will thoroughly enjoy this, then.

I've only used their GUI frontend myself, but ILSpy is also available as a library and command line tool.

As you can see IL code is not exactly human readable, and it's also quite verbose. If you want to have an idea of how your code looks like in IL you can use a decompiler tool such as JustDecompile or ILSpy.

Take a random piece of C# software, run it through ILSpy, and be amazed at the results.