“People think that its purpose is to present the game to everyone around the world, but actually, it's not. It's to show the staff.”
Kojima said the hidden purpose of his early teasers is that he always releases one long before the game is finished to show the world view, the music and the colours, and although people think the teaser’s purpose is to present the game to the world, its real purpose is to show the staff; development lasts three or four years, during which people marry and have children and want to know what kind of world they have thrown themselves into, and the teaser tells them what they are doing so they can finally tell their families “I’m on that; I did that part” and receive praise — a boost in morale that will last for three years.
“I always release a teaser long before the game is finished to show the world view, the music, the colours, etc. […] during those three or four years, you really want to know what kind of world you've thrown yourself into. […] And this boost in morale will last for three years.”