JavaScript for scheduling my gaming plan every day

ScheduleGame.js

/ connect the day number with a main game. 0 = sunday
var mainGames = { 
  0: "XCOM 2", 
  1: "XCOM 2",
  3: "The Witcher 3", 
  5: "XCOM 2" 
}
var randomGames = [
  "Otherland", "The Secret World", "Otherland", "Elite Dangerous", 
  "Star Drive II", "Wildstar", "City Skylines", "Anno 2270", 
  "Predestination", "The Witcher 3", "Beyond Earth", "Civilization V",
  "The Elder Scrolls Online", "Pillars of Destiny", "Thea - The Awakening"
  ];

function selectRandomGame() {
  var n = randomGames.length
  var i = Math.floor(Math.random() * n);
  return randomGames[i]
}

function selectMainGame() {
  var date = new Date()
  var day = date.getDay()
  return mainGames[day]
}

function ISODateString(d){
  function pad(n){return n<10 ? '0'+n : n}
  return d.getUTCFullYear()+'-'
      + pad(d.getUTCMonth()+1)+'-'
      + pad(d.getUTCDate())
}

function ISODateTimeString(d){
  function pad(n){return n<10 ? '0'+n : n}
  return d.getUTCFullYear()+'-'
      + pad(d.getUTCMonth()+1)+'-'
      + pad(d.getUTCDate())+'T'
      + pad(d.getUTCHours())+':'
      + pad(d.getUTCMinutes())+':'
      + pad(d.getUTCSeconds())+'Z'
}

function createGamingEvent(agent, maingame, randomgame) {
  var today = new Date();
  var day = today.getDate();
  var month = today.getMonth();
  var year = today.getFullYear();
  
  var dayOfTheWeek = today.getDay()
  
  // normally, I train on Sunday (day 0 ) at 10
  var startHour = dayOfTheWeek == 0 ? 15 : 19
  var endHour = startHour + 1
  var startDateTime = new Date(year, month, day, startHour, 0, 0, 0)
  var endDateTime = new Date(year, month, day, endHour, 0, 0, 0)
  var description = ""
  if (maingame == null) {
    description =  "Your game for tonigh was selected: \n\n"+
                    "****  " + randomgame + "****\n\n" + 
                    "Have fun!"
  } else {
    description = "Please continue your main game: \n\n" +
                  "**** " + maingame + "****\n\n" + 
                  "If you have enough time and I assume you haven't, play this game: \n\n" +
                  ">>>> " + randomgame + "<<<<\n\n" + 
                  "Have fun with both games!"
  }
    
  agent.createEvent({ 'message': 
      { 'summary': "Dein Spiel für den Spieleabend wurde definiert",
        'visibility': 'default',
        'description': description,
        'start': {
          'dateTime': ISODateTimeString(startDateTime)
        },
        'end': {
          'dateTime': ISODateTimeString(endDateTime)
        }
      }
    });
}

Agent.check = function() {
  var maingame = selectMainGame()
  var randomgame = selectRandomGame()
  this.log("Maingame: "+maingame)
  this.log("Random Game: "+randomgame)
  createGamingEvent(this, maingame, randomgame)
}