By Zilpha Keatley Snyder (1967)

WHEN I was a boy of 12, I had two friends. With one of them I did real-world things. We would take the train into New York City (then a safe enough place for middle-class kids from the suburbs) and go to double-feature movies. We sailed in boats on the fringes of Long Island Sound.

With my other friend, though, I lived almost entirely in an imaginary world. Many afternoons a week we would come home from school and instantly take up our roles in a sort of medieval kingdom. Note the plural. He might be an enemy king at 4 p.m., the captain of our palace guard at 4:10, a rebel duke at 4:53, and (very reluctantly) a beautiful princess just before whichever of us had to go home. Some female roles were needed, and we played everything. Just once we tried admitting the boy who liked double features and sailboats. It was a dismal failure. He never even managed to perceive his broomstick as a lance.

One of the great divisions among children is between those who go on liking to play pretend games after the early years (all very small children play them) and those who by 8 or 10 see such games as foolishness. I'm not claiming that one kind is better than the other, certainly not in the sense of pointing to a richer or happier life. Gordon, the boy who liked reality and scorned his broomstick lance, has been far more successful than either Jack or me. He has half a dozen enterprises, all thriving. We both became what the Japanese, putting in an r for the l, call sararimen -- minor employees of large organizations.

But I do make the modest claim that it is well to know which kind of child you are dealing with, before you drop into a bookstore to get the kid something for his birthday. And if the child happens to be a role-player, between ages of about 9 and 15, I do have a book to suggest. Get that child Zilpha Keatley Snyder's The Egypt Game (Macmillan, $13.95; Dell paperback, $3.25).

There are tons of books about imaginary worlds. I love most of them. Most of the well-written ones, anyway. But in nearly all cases the imaginary world is entered either by magic (you walk right into a painting, you climb a beanstalk, you drink a potion) or by science (you arrive in your starship). Either way, the world was already there, and it is merely a matter of reaching it. But in The Egypt Game, the world is not a pre-existing one. It is created by its characters. Watching them do it is the very best part of the book.

The first creator you meet is an 11-year-old girl named April Hall. April has just arrived in northern California to spend what she erroneously supposes will be a few weeks with her grandmother. She didn't want to come. She has liked it just fine, living in Hollywood with her glamorous mother, a bit player in the movies. Grandma's only a librarian, at what seems to be the University of California at Berkeley. April is precociously bright, wears huge false eyelashes, talks grown-up and in general is sure to annoy any normal healthy child.

She doesn't annoy Melanie Ross, though. Melanie's a girl her own age whose family live in the same small, shabby apartment house as April's grandmother. Melanie is a born role-player who has never happened to meet someone like herself, and so has always gone alone into her imaginary worlds. She instantly recognizes April as another of her kind, and welcomes her, eyelashes and all.

By the fourth chapter the two girls are close friends. They play together every day. Just now they're talking a lot about Egypt -- they're even going to the city library and reading up on the old Egyptian gods and rituals. At the end of the chapter they begin to create their world.

What makes it all possible is Melanie's discovery of a loose board in a fence surrounding a storage yard. The yard is behind a run-down antique shop, and in it are many suggestive things: a crumbling bust of Nefertiti, queen of Egypt; a lot of wooden columns from some dismantled house; a shed that almost demands conversion to a Temple of Sacrifice. Within minutes the game begins.

It rapidly develops over the next few weeks. April and Melanie use the bust of Nefertiti to decorate their first altar, which soon comes to belong to Isis, goddess of goodness and beauty. Next they are inspired (April particularly) to make an altar for Set, god of evil. They begin to make sacred fires in an old mixing bowl. They find the Crocodile Stone, and dedicate it to Set. Before many weeks, they almost begin to believe in the power of what they have evoked. Please note the "almost." There are no cheap Stephen King thrills in this book, with the bust of Nefertiti coming eerily to life, or the mixing bowl being haunted, or whatever. The thrills in The Egypt Game are more expensive, and much more plausible. And mixed with a good deal of comedy. This book is funny, as well as highly imaginative.

But though Nefertiti doesn't come to life, the game itself does; and like any living thing, it keeps growing. In the beginning there are just April and Melanie, plus Melanie's 4-year-old brother Marshall, whom she has to take care of after school, because her mother is off teaching and her father is a graduate student at the university. Marshall is happy to be a boy pharoah. THEN a new girl Elizabeth Chung moves into the apartment house, and turns out to have a good Egypt potential. Chung, did I say? She's Chinese-American? Yes. Melanie and Marshall are black, for that matter, and a Japanese-American boy will be along shortly. This is no virtue-book, however, preaching ethnic tolerance. Human diversity is something it takes casually for granted. It's entirely for her own sake that Elizabeth gets admitted to the priesthood of the Land of Egypt.

Somewhat later the three high priestesses and the boy pharoah are joined by two high priests. That is, on the night of Halloween, two boys from their sixth-grade class discover the fenced yard, and promptly invade. At first they threaten to tell, but one of them in particular is fascinated by the altars of Isis and Set, and by the rituals the girls have devised. All this appeals to his own fertile mind. In the end, Toby Alvillar and Ken Kamata join up.

Ken's role is rather like that of Gordon in my own childhood, but Toby is a full participant. He is the one who now introduces all the Egyptians to the study of hieroglyphics, and it is he who gets so carried away with the Oracle of Thoth that all six Egyptians scare themselves half to death.

Wouldn't you be a little nervous, if you started leaving written questions in the beak of a stuffed owl that you are pretending is the god Thoth, and the owl starts giving written answers? Wouldn't you be even more nervous, if you were Toby who had been sneaking out at night to write the answers, but the third night you couldn't get out, and there was an answer anyway? In a strange handwriting? Saying something it would seem as if only a god could possibly know? I think you might be.

Zilpha Snyder is justly famous for her ability to invent realistic and likeable child characters. All six of the main characters here are a pleasure to read about, including Ken, the all-American athlete. As for the game itself, it sounds wonderful. I wish Jack and I had been in the Land of Egypt, instead of our nameless and eventually rather boring medieval kingdom. If I wasn't afraid the sixth-graders would laugh, I'd go now.

In fact, maybe I was wrong to say that this book is for one type of kids between the ages of 9 and 15. Though grown-ups would read it differently, with reminiscent smiles, it may really be for one type of people, up to the age of 100 or so.

Noel Perrin is the author of "A Reader's Delight" and other books.