Ben Croshaw on the problem with walking simulator games:
Video games don’t have that very basic necessity - the ability to naturally control the pace of the story. There’s only so much the creator can do when ultimately the player is the one in control. If they had total freedom then they might just gazump all the way to the ending and miss boatloads of things that were all carefully placed to in some way pay the story off. That, friends, is where challenge comes in. Challenge is the means by which video game creators naturally structure the experience. Whether it be a fight you need to be good enough to win before you can enter some area or another, or a puzzle that requires careful exploration of the environment and understanding of what needs to go where.