[driekwartappel]

This looks like the minimal:

  class HelloWorld
  {
    static void Main()
    {
       System.Console.Write("Hello world!");
    }
  }

Try it online: https://tio.run/##Sy7WTc4vSv3/PzknsbhYwSM1Jyc/PL8oJ4WrmktBob...