opensde-nopast/lib/misc/hello.cs

// Hello World in C#
// Compile into an assembly with  'mcs hello.cs'.
// Run with the Mono Interpreter  'mint hello.exe' or
//     with the Mono JIT Compiler 'mono hello.exe'.

class Hello
{
   static void Main()
   {
      System.Console.WriteLine("Hello World! (A simple C# program.)");
   }
}