Actors

Before I go much more deeply into the mechanics of world-building, I'd like to consider another element that goes into games and worlds. As I will use it, an "actor" is someone or something that is capable of originating an event. Players are considered actors. Single-player games and solitary worlds can be interesting, but games involving two or more actors are considered more so. These actors typically represent animals (such as monsters), or people. Usually, one or more of the actors is controlled by the computer and there is a set of rules determining when or how each of them acts. Some are intelligent, some not so; some have complicted behavior, others are quite simple.
The simplest form of action is autonomous: every time step, actor a (does action_1). The next is conditional: If (somecondition_1) then actor a (does something_2). More complicated conditions and more complicated actions begin to go into the subject of artificial intelligence, which I'm going to dodge for now.

Of the games I've mentioneed,

Single actor games: Pong, Lunar Lander;
Two actor games: Tic-tac-toe; Spacewar; Baseball;
Multiple actor games: Oregon Trail, Star Trek, dnd, and Dungeon.

In the history of games, I've reached 1976. Video games included Breakout, probably inspired by PONG, and Night Driver. ADVENT, sometimes called Adventure, sometimes called Colossal Cave, was the progenitor of a whole series of interactive fiction or text-adventure games.
Also in 1976, Creative Computing magazine began publication, and for a few years published a series of "The Best of Creative Computing", which include even more samples of computer games.
For the past few days, I've been reworking a classification of the games published in BASIC Computer games, (see the sidebar). All these give me enough of a variety that I'm going to set history aside and take a closer look at the different farieties, since some of them will be more closely connected to my purposes than others.