In real life, the edges of perception are where everything starts to kick in. Across that threshold is where our minds and our emotions run away with themselves, struggling to fill in the missing details and so make sense of the world. This is the realm of the uncanny, where objects materialize out of blind spots and scare the wits out of us, where spirits and monsters threaten to live, where optical illusions and magic tricks make us question what we know of the world. It’s these moments that suggest to us that there’s more to life than we’ve been led to understand. How we respond to that notion depends partially on our own personalities, and partially on the context.
Likewise, even in the closed system of a videogame there is only so much that a designer can draw, and only so many variables that a designer can define. Even in the simplest games it’s tough to account for everything and simple for the player to find a thread to pick away at — say, a seam in the geometry or a weird bit of physics. And then the more possibilities that you suggest, the more that the mind will begin to drift and wonder what else is out there, what else is possible.
Technical limitations also play a role, in that they draw a certain line over which the world cannot possibly exist. When the game presses up against those limitations, as in a late-era console game — your Streets of Rage III, your Silent Hill — you get a certain crackly pressure. Subconsciously you can feel the game straining to make its case, due to the mismatch of the game’s idea of reality and the reality imposed on the game by the hardware.
The NES is a fun object lesson, as from the moment it hit US shores it was outdated, its games bending the rules all over the place just to exist. On its own the NES isn’t all that much stronger than, say, a Colecovision. Every new feature that came along — horizontal scrolling, vertical scrolling, cutscenes — meant more custom memory chips. By the early ’90s the average NES cartridge was practically a console in itself; the NES itself acted more as a copy-editor, checking to make sure the input made sense then passing it along to the TV screen. So for most of its life, just about every game for the system has an unnerving glitchiness just under the skin, threatening to break loose and disrupt its carefully argued reality. Sometimes, as in Metroid, those glitches become as much a part of the game as the intended rules, suggesting untold depths that perhaps nobody has ever explored before.