God damn people, read about the game if you are so confused.
Two people play. One person is the 'writer', the other is the 'actor'. The writer sets a scene and puts a character in it using a library of icons and settings. They can also illustrate any objects/characters/animals/etc they want as well, and have this ability throughout the game. Now, turns switch, and the actor can tell the writer what they want to happen. The writer's turn then follows, and they can either heed the actor's requests, or can do their own thing if they want.
The only rule is that there is a time limit for each turn. So let's say the scene is a room with a woman in it. The actor can say "the woman summons a demon", at which point the writer, who let's say decides to heed the actor's request, must then draw a demon if there isn't one in the library, and can also give it a sword if they want to.
The idea is that you write a dynamic story with a friend, and that the story can literally go anywhere and be anything. If you play it with any level of seriousness, it promises to be, at the very least, surprising. It is, of course, not for everyone, and many people may not even consider it a 'video game' in the 'classic' sense.
EDIT: Here is a (fairly pretentious) article about a game that an IGN writer played with the creator:
http://pc.ign.com/articles/107/1079328p1.html
It really illustrates how the game mechanics function.
It is also worth mentioning that I am really quite astonished by the harsh outcry from a few of you regarding the minimum price. It is $1.75. What are you doing with a

ing credit card if $1.75 is so heinous? And to go and argue the validity of referring to this pricing option as "name your own price", as though he has somehow offended you by doing so? Wow. Have you somehow forgotten that "name your own price" almost always does not mean that you can pay nothing? That means that there is a minimum of .01 on all "name your own price" purchasing plans. Does that somehow offend you as well? How dare they refer to it as "name your own price" when you don't even have the option of NOT PAYING ONE, right?