Scout doesn’t enjoy the game as much as the boys because she doesn’t like the parts she is given.
Before Dill comes into their lives, Scout and Jem act out books. When Dill joins, he gets the parts formerly played by her. Scout starts to feel left out when the game switches to the Boo Radley storyline. Boo Radley is a local legend. He is a neighbor who never comes out of the house. In their game, they re-enact his life. Scout gets left playing various female characters “reluctantly.”
I never thought it as much fun as Tarzan, and I played that summer with more than vague anxiety despite Jem's assurances that Boo Radley was dead and nothing would get me … (Ch. 4)
Scout is afraid of Boo Radley. She believes the hype. Jem has given her a scary description in which he feeds on the raw flesh of dead cats and has a jagged scar on his face. She does not enjoy the game of making him come out, because she does not want him to come out. She is afraid because she is younger than the other two and not quite ready to give up believing.
There was a long jagged scar that ran across his face; what teeth
he had were yellow and rotten; his eyes popped, and he drooled most of the time. (Ch. 1)
As childish as it might be, Scout is young enough to still be frightened by Jem's tales like this.
As the old saying goes, three’s a crowd. With Dill in the picture, Scout gets accused of being a girl, which is an insult to her. She is younger than Jem, but usually close to him. Yet when Jem has Dill to hang around with, she sometimes feels like the odd one out. Scout becomes a third wheel to the two boys, and feels like Jem naturally would rather hang around with a boy, even though Dill and Scout are closer in age. Dill seems to want to make Boo Radley come out, and Jem is old enough to not be frightened of him and just enjoy the story.