Video games and Originality

When you buy a game and play it, lets pretend that game is something new. Now lets say that new game that you bought is part of an already existing genre. So for the sake of this example lets say you bought Dying Light, a zombie horror survival game with the feeling of Parkour and Dead Island. You would think a game that has all these features in the genre would be considered an original idea of some kind right? Well not exactly. See my question is, what defines originality in video games? Dying Light technically is still a zombie survival game, and it's concepts it uses have been used in other games outside of the zombie genre. So are the cool things you can do in Dying Light actually original? In some cases you can say that yes Dying Light is original in terms of the zombie and survival genre. But when it comes to a comparison of all other games outside of the genre, thats when you notice, that this games concept has been used in some other games, just not with the zombie theme. So my question to you is. What makes a game original to you? Like what defines originality in your opinion regarding video games?