The use of affiliate marketing

Affiliate marketing is a style of marketing through a third party, You don't generate the audience, the third party does.
Essentially this is the kind of marketing most known as "Collaborations" or "Partnerships".
You may make a game and have someone who has their own audience come play it - this means if they do it publicly they are sharing your game through their platforms allowing you access to communicate with their audience - some of which may never heard of you or your game before. This can be great as cross-pollination but can have background costs i.e. the business end can get very messy as people perceive things differently for pricing and views and such. This is also where the conversation of #AD comes up in the world of youtube. #AD came up as it became a legal requirement to tell someone when they are being sold a product as some are very cleverly disguised. An Affiliate is someone who is connected to a product but only through deals - they don't have any say on the product other than public / personal commentary.