Given the very wide ranging import of postcolonial criticism, this question could be answered in a number of different ways. In one sense postcolonialism is about celebrating voices from the formerly colonised nations and the bringing to light of situations and issues that are relevant to such unique environments. In this sense, Anita Desai is a famous postcolonial author, emerging as she does from India, which was a colony of Britain for so long.
However, we might want to extend this basic analysis by refering to the way in which the story's theme establishes the alienation of the individual and the way that this could be argued to present the situation of so many postcolonial subjects who struggle to find their identity and meaning in life. The epiphany that Ravi experiences at the end of the story, when his dreams of victory and glory are cruelly squashed by the contempt with which he is treated by other children, focuses on his own inner insignificance, as the final paragraph makes clear:
He would not follow them, he would not be included in this funereal game. He had wanted victory and triumph--not a funeral. But he had been forgotten, left out, and he would not join them now. The ignominy of being forgotten--how could he face it? He felt his heart go heavy and ache inside him unbearably. He lay down full length on the damp grass, crushing his face into it, no longer crying, silenced by a terrible sense of his insignificance.
The irony of this passage, and the way that Ravi has technically won the game but it was abandoned long before he emerged, meaning that he is ignored instead of being feted for his victory is keen and biting. Likewise, there is irony in the way that he refuses to play the funereal game with the other children, but presides over his own death of his innocence and hopes. Some critics would argue that this epiphany and the situation of Ravi explicitly relates to the postcolonial subject, who finds himself cast adrift in a sea of meaninglessless and insignificance, with the firm ground of identity provided by colonialism swept away.