Chris Baraniuk, over at The Machine Starts (an allusion to the excellent short story by E. M. Forster), eloquently explains the "fifth wall" of games that some players always feel the need to transgress.
Like many other games of the era, Super Mario 64 set each level on a kind of pixelated island surrounded either by high blurry walls of green (an abstract representation of trees) or, better, an invisible perimeter which allowed you to look out at endless sea or space beyond. This was particularly prevalent in a later game in the Mario series: Super Mario Sunshine, on the Gamecube.
But standing there, in the sunlight, looking out towards the horizon, or into a bottomless abyss, one felt vitalised by the illusion that the invisible walls and protecting barriers had been arbitrarily put in place. That what you were staring at wasn't just there to give the game level some spatial context, but that it was in fact the landscape of a very real (virtual) universe into which you might, somehow, escape and wander. Even though these no-man's-lands were empty of enemies and useful items to collect, their vastness and the idea that you 'weren't supposed to be there' were at times more tantalising than the game narrative itself. So you tried to get there. You tried to break the fifth wall.
It's a powerful allure—the ever-elusive space behind the screen, beyond the developers' intended boundaries. In conceiving the idea of 'cyberspace,' author William Gibson saw that what gamers wanted "was to be inside the games, within the notional space of the machine...and the machine in front of them was the brave new world."
In many games, the fifth wall is an invisible one that beckons to be crossed. It's hard not to feel like the last great explorer, pushing back at God, in search again of the uncharted.