FizzBuzzInCSharp7.cs

using System;

namespace FizzBuzz
{
    class Program
    {
        static void Main(string[] args)
        {
            for(int i=1;i<=100;i++) {
                switch ((i % 3, i % 5)) {
                    case System.ValueTuple<int, int> t when t.Item1 == 0 && t.Item2 == 0:
                        Console.WriteLine("FizzBuzz");
                        break;
                    case System.ValueTuple<int, int> t when t.Item1 == 0:
                        Console.WriteLine("Fizz");
                        break;
                    case System.ValueTuple<int, int> t when t.Item2 == 0:
                        Console.WriteLine("Buzz");
                        break;
                    default:
                        Console.WriteLine(i);
                        break;
                }
            }
        }
    }
}

You can change your case System.ValueTuple<int, int> t expressions to case var t

I'd prefer a to stick with LINQ and named tuples.