This in javascript normal function

Question

I was studying this keyword in javascript when I came across this example

const TESgames = {
  titles: ['Arena', 'Daggerfall', 'Morrowind', 'Oblivion', 'Skyrim'],
  seriesTitle: 'The Elder Scrolls',
  listGames: function() {
    this.titles.forEach(function(title) {
      console.log(this.seriesTitle + ': ' + title);
    });
  }
};

TESgames.listGames();

Here why is this.seriesTitle undefined.

From my understanding, context of this depends on the function which is calling it? Does forEach and other function (like .map) etc always depends on global scope? that's why it is undefined