The short story "Games at Twilight" by Anita Desai features only one character who is both round and dynamic and two others who can only be categorized as round.
Round and dynamic characters are usually the leading personas in a genre. Their presence in a story or text informs and entertains the reader and gives depth to the writing. The two terms, however, are not the same, though they are sometimes regarded as such.
A dynamic character is one who undergoes change as the story unfolds. In this sense, the character is, in the end, different from the one encountered at the beginning.
The term round character, however, refers to a person who has a rich and interesting personality—one who is believable to the audience and presents much intrigue. Such a character, one could say, is complex. This character's personality, actions, attitudes, and so on would have been formed by a variety of experiences and encounters.
In this short story, the protagonist, Ravi, is the main focus. He is clearly a round character, because the author exposes details about his personality, his thoughts, and his actions. The audience knows exactly what Ravi is thinking and how he assumes the game will play out. We learn that he is ambitious and wants to be admired. In the end, however, Ravi is bitterly disappointed, because things do not turn out as he wanted them to. It is for this reason that he can be dubbed dynamic.
Although some detail is provided about Mira and Raghu, they remain the same throughout the story. They have not undergone any significant change, nor have they learned anything new. The details about their physical appearance, their actions, and their personalities make them rounded.
All the other characters, though, are flat, since we don't learn much about them.