Adventure games make frequent and varied use of doors -- some doors require us to find a specific key, some "doors" are represented by guardian characters demanding payment or favors, and some constitute logical or mechanical puzzles in and of themselves.
Multiple vintage adventures required the player to slip a newspaper or mat or other flattish object underneath a door, then dislodge the key inserted in the keyhole on the other side (often hinted at only by the player's inability to look through the keyhole), pulling the object back out to claim the prize. Some games featured a lockable "safe room", where the player was encouraged to turn the door to his or her own advantage, securing critical items against thieving NPCs.
Whether by intent or accident, Scott Adams' early microcomputer adventure Mystery Fun House was already going meta in this regard, with mixed results.
Mystery Fun House takes place in a carnival funhouse, featuring several hidden passageways and a plethora of doors.
Some of the doors are hidden and must be discovered by solving puzzles. And some of the doors visibly on display can't be opened at all.
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While the doors that are functional are satisfying enough, this early game establishes that unrealizable possibilities have an unfortunate side effect. We've spent considerable time exploring the game world and building a mental map of it, graphing out all those places where a closed and locked door appears to be keeping us from exploring new territory. As a result, the game's finale is somewhat abrupt and unsatisfying -- even though we've won according to the designer's rules, our brains are left confused and vaguely frustrated, thanks to those nagging unopened doors. Real life provides little enough closure in the emotional realm, but humans have evolved to believe that any space we inhabit will eventually reveal its geography; a game that confounds that expectation just feels wrong somehow.
Shigeru Miyamoto's seminal fantasy game features numerous stairways and dark passages, and its gameplay celebrates exploration.
The world above ground and the dungeons below complement each other, and both feature hidden paths waiting to be discovered. Our hero Link can push stones, burn trees and kill enemies to find doors, and use bombs to blow holes in dungeon walls to create new pathways, often suggested by suspicious "holes" in the official map.
Unlike most of its action-oriented peers on the 8-bit NES, The Legend of Zelda encourages and expects the player to experiment, to try things that might just produce an unexpected result.
For instance, there are six identical armored enemies in this room that can be awakened and fought, but only one of them happens to be concealing a stairway to special item shop:
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Humans have been globally successful in part because we are willing to take risks and learn from our results -- we can surmise that, at some point in our species' pre-history, somebody took a successful chance and ate an egg, and somebody less fortunate swallowed cyanide. Miyamoto's design capitalizes on our chimpanzee brain's need to goof around and just see what happens.
"Doors" in the Zelda universe are not always obvious barriers, and they may not even be visible until some sort of puzzle is solved. But they do provide structure to the experience, and more importantly they often materialize to reward us for trying things out at random.
For all the memorably choreographed setpieces in Capcom's original Resident Evil -- zombie dogs crashing through windows, that first encounter with the snacking undead -- most players' memories are also filled with...
Rendered in polygonal 3D, and used primarily to cover substantial loading times on the original PlayStation, numerous animations of opening doors serve to prepare (or disarm) the player for what lies beyond.
Some doors require us to find keys, or perform puzzle-solving tasks in the old-school tradition. And the first time we pass through any given barrier, we don't know whether the other side will be eerily quiet and still, or bring us face-to-face with a shambling animated corpse. As a result, this simple, utilitarian moment kicks the suspense up a notch every time we see it:
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Mirroring, perhaps, the realities of our ancestors' mental framework, we're never expecting a radically new experience when we pass through a door in the old mansion. But our brains are clearly preparing for an unknown and very likely dangerous environment on the other side. The effect is heightened by the game's ponderous loading times -- seconds for the door to appear, seconds for the animation to play, more seconds for the fade out. By the time we're back in control, we're paranoid from the sheer suspense. The effect of passing through any specific door wears off over time, as once we've been through, our mental map is populated and we know where we'll be when we get to the other side. But on occasion Resident Evil takes sadistic advantage of this, and we find out that dangerous changes have occurred while we were away.