Word-of-mouth is marketing too. Perhaps you are thinking that marketing === advertising? Because marketing doesn't have to be advertising. Building a community, attending conferences, getting influencers to play your game - these are all marketing activities. If people are talking about the game, it's surely fueled by a quality experience but marketing has to bootstrap that conversation.
Word-of-mouth might be marketing, but it's not something you can work towards. To get that you need a good fun game. IMO that's not a marketing effort, it's a symptom of a good unique game.
I'm not a marketing expert tho, but I can't think of any way to force word-of-mouth onto people.
the game's quality acts like a force multiplier for word of mouth, essentially you're more likely to promote or talk about a game you enjoyed. But you need some critical mass for that to have any real impact. What good is it if each player refers 1.5 others on average, but you only get to 5000 before the game becomes old news? Most games don't continue to sell forever and the hype will die out eventually, so you want that hype to reach a large audience quickly.
Word-of-mouth is marketing too. Perhaps you are thinking that marketing === advertising? Because marketing doesn't have to be advertising. Building a community, attending conferences, getting influencers to play your game - these are all marketing activities. If people are talking about the game, it's surely fueled by a quality experience but marketing has to bootstrap that conversation.