"Games at Twilight" by Anita Desai is a touching and very well-written account of Ravi, who learns a profound life lesson while playing a classic child's game of Hide 'N' Seek. The story recounts, in detail, Ravi's excitement at having found an excellent hiding place, his giddy anticipation at emerging triumphant and all-glorious after beating out the bully Raghu, who was the seeker. Unfortunately, he daydreams a bit too long, and by the time he emerges, the other children have moved on--they have completely forgotten about him. It is at this point that Desai inserts the profound and moving lesson that Ravi learns that day:
"The ignominy of being forgotten—how could he face it?...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."
So, to finish the sentence given above, there are several different possibilities. You could try "the childish games are actually training grounds for coping with disappointment in later life." This reflects how Ravi is being exposed to disappointment through a game, which will give him experience with it in future, real-life encounters. Another possibility is that "the childish games are a microcosm of real life, representing many aspects that children will enounter as adults." Consider Raghu, a representative for every mean, unfair bully that you might meet in the workplace or in everyday life. Consider Ravi's foolish and vain day-dreaming, a symbol of the frailty and uselessness of vanity. Consider the crowd of children, who forgot him, symbolic of how most life moves on very quickly, even when you are upset. The entire game with its characters and events can correlate to real-life situations people enounter.
Those are just a couple possibilities of ways to finish off that sentence, and I hope that they help to get your wheels turning. Good luck!