YOU SAID:
My brother is playing a mobile game
INTO JAPANESE
私の兄は携帯ゲームをしています
BACK INTO ENGLISH
My brother is playing mobile games
INTO JAPANESE
私の兄はモバイルゲームをプレイしています
BACK INTO ENGLISH
My brother is playing a mobile game
INTO JAPANESE
私の兄は携帯ゲームをしています
BACK INTO ENGLISH
My brother is playing mobile games
INTO JAPANESE
私の兄はモバイルゲームをプレイしています
BACK INTO ENGLISH
My brother is playing a mobile game
it is unlikely that this phrase will ever reach equilibrium