something or someone that affects the result of a game very much

As a player he can be a game changer. 作为队员他可以是一名改变比赛结果的人。

something such as a product or event that affects a situation or area of business very much

The hit show has been a game changer for the network. 这一热门节目很大程度上改变了这家电视网络。