Can you use Visual Studio to code in pure C# without using .NET libraries or classes?

Visual Studio is primarily designed for development in .NET languages, and C# is one of the main languages used within the .NET ecosystem. While C# itself is tightly integrated with the .NET libraries and runtime, you can certainly write code in C# without relying on specific .NET libraries or classes, but it's important to understand some aspects of the language and tooling.

Here are a few considerations:

1. **Console Applications:**
   - You can create console applications in C# without relying on extensive .NET libraries. A simple console application may only use basic language features without delving into the broader .NET framework.

2. **Limiting Dependencies:**
   - While you can write C# code without relying on many .NET libraries, some minimal dependencies are typically required for basic functionality. For example, input and output operations often rely on the `System` namespace, and you may use the `System.Console` class for console interactions.

3. **Language Features:**
   - C# itself is a rich and expressive language, providing features such as classes, structs, interfaces, generics, and more. You can leverage these language features without necessarily using advanced .NET libraries.

4. **Targeting .NET Core or .NET 5+ for Lightweight Applications:**
   - If you want to avoid the full set of .NET libraries and target a more lightweight framework, you can use .NET Core or .NET 5+ with a minimal set of dependencies. This allows you to create console applications with reduced reliance on the broader .NET framework.

5. **Use of C# as a Scripting Language:**
   - With the introduction of C# scripting (using .csx files), you can write C# code in a script-like manner, without having to create a full-fledged project. This can be useful for experimenting with C# code without relying on extensive libraries.

Here's a simple example of a console application in C#:

```csharp
using System;

class Program
{
    static void Main()
    {
        Console.WriteLine("Hello, C# without extensive libraries!");

        // Your code here without relying on additional libraries
    }
}
```

Keep in mind that while you can minimize your reliance on .NET libraries, it's often beneficial to leverage the extensive libraries and frameworks provided by the .NET ecosystem for practical application development. If your goal is to write code without any dependencies, you might explore other languages that are designed to be more lightweight and independent.