This is a nice article about Jason Shiga, who was inspired by the
choose-your-own-adventure books, where every page has some choices you can make that instruct you to turn to different pages which alter the storyline. Jason has been stretching the idea to introduce some more complex ways of interacting with comic stories.. One even has a kind of "inventory" system.
Every page is sliced in half, separating the comic into two parts. The top half is where the story unfolds, while the bottom half displays the contents of your suitcase. The two sides are connected by an intricate system of page-turning: When you see a number inside a square, you flip to a page in the top half of the comic, advancing the story; when you see a number inside a circle, you flip to a page on the bottom, adding and removing items from your suitcase.
Very cool stuff -- seems like these comics would make great mind-expanding gifts for young kids.