I think the Ingram reviewer above was on something when he wrote of the "danger" that grew from the sisters' game, and of the "evil man determined to control their thoughts". I didn't get any of that out of _The Game_.
_The Game_ is basically the story of two sisters: Julia, a sociable but shallow novelist who writes about the boredom of domestic life; and Cassandra, a nunlike scholar who hides away from real life in the cloistered world of high academia. The "game" referred to in the title is an imaginary Arthurian world invented by the sisters when they were children, but it has little bearing on the rest of the novel, except in that Cassandra went on to become an Arthurian scholar, and Julia uses it as an example of Cassandra's condescension. It could have been dropped from the plot without much effect, which is sad for me, since the Arthurian element is the biggest reason I wanted to read the book in the first place.
Leaving out Arthur, who is mostly irrelevant anyway, we have Julia and Cassandra, who are just repairing their estranged relationship, when Simon Moffat comes back into their life. Simon was both women's first love; Cassandra adored him from a distance, while Julia slept with him. This triangle was the reason for their estrangement. When he reappears, so do the tensions between the sisters.
_The Game_ failed to engage me; most of the characters were pretty one-dimensional and cold. Cassandra had a few moments of stunning dignity, but she didn't seem real either. A.S. Byatt has gotten much better since.