Distance

One of the basic quantities that's needed to work with a virtual world is some notion of the distance between two points. There are two principal variants on this. One of them ix the usual Euclidean distance, D = sqrt((x2 - x1)*(x2 - x1)+ (y2 - y1)*(y2 - y1)). Another one is called the Manhattan, taxicab, or city-block distance; D = abs(x2 - x1) + abs(y2 - y1). There are various others possible, but these are reserved for more advanced work.

Pushing the historical studies of games for a moment, I find the history continuing in 1975, with another, apparently independently developed game called Dungeon, written by Don Daglow. I find that he was also the author of Baseball, which I mentioned and passed over earlier.