YOU SAID:

My brother won't let me play his game.

INTO JAPANESE

兄は私に彼のゲームをさせないでくれ。

BACK INTO ENGLISH

My brother shouldn't let me play his game.

INTO JAPANESE

私の兄は私に彼のゲームをさせるべきではありません。

BACK INTO ENGLISH

My brother shouldn't let me play his game.