Racing the Beam : the Atari Video Computer System - Index of

in the PDP-10 Adventure, although those are portrayed using word rather
than image.
Confusing spaces have frequently been seen in action-adventure
games. The Legend of Zelda took Adventure’s four-directional maze pattern
and added a set of movements through the same maze as a symbol for
fi nding its exit. These “lost woods,” as they are called in the fi rst version
of that game, trap the player completely until the proper sequence of
directions (up, left, down, left) is discovered, allowing escape. The traversal
of space has become a standard way to require the discovery of a
particular input sequence, something that had been previously done
through the subtlety of language.
Another method of spatial confusion introduced in Adventure is
occlusion. In early text adventures, rooms and caverns are often dark and
their contents and exits are not visible. The player was typically able to use
a lamp or some other light source to illuminate these areas, whose contents
would then be described with text.
In a text adventure, illumination is usually all or nothing: a room is
either lit or dark. But this design doesn’t work for a graphical game like
the VCS Adventure. A dark room would just be a black screen. The text
adventure always provides a facility for direct input—the text prompt—but
there would be no obvious graphical analogue in a totally dark room in the
VCS Adventure.
Robinett managed to implement occlusion using a different method,
one that would come to be called “the fog of war” in later adventure and
strategy games. “Fog of war” is a military term that refers to the ambiguity
and confusion experienced in the theater of war. In games, it usually
refers to a lack of visual information on a map. Areas that have been
explored or settled become visible, whereas those that have not remain
shrouded or entirely black. Board games like Stratego implement a kind
of fog of war by hiding the identity of opposing units. Tabletop miniature
games often track the location of units like tanks on a separate record or
even a separate board.
Variations 2 and 3 of Adventure introduce catacombs, which take the
form of an orange labyrinth. These catacombs are darkened, and the
player can only see the maze’s walls within a small distance around him.
To accomplish the occlusion, Robinett simply made the fl oor and walls the
same color. The walls in Adventure are drawn, after all, using playfi eld
graphics. The color for the playfi eld and the background are set by writing
the same eight-bit color value to each of two registers, COLUPF and
COLUBK. The ball always takes on the color of the playfi eld, which explains
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