I don't think it's good for my son to be playing games so much
I don't think it's good that my son plays games all the time
My son plays games all the time
My son plays games so much
息子がゲームをばかりやる
I don't think it's good that my son 〇〇
I don't think it's good for my son to be 〇〇ing so much
息子が〇〇することを私はよく思わない
個人的に1番目を使います。not good for himと言う表現は、体に悪い、不健康的と言うニュアンスが含まれているからです。
ご参考になれば幸いです。