In your example, 'play on' is used as a noun, but the meaning is derived from the phrasal verb, 'play on'. Therefore, the normal meaning of 'play' is altered.
play on [phrasal verb] also play upon
play on/upon (something)
: to make people do what you want by using (their emotions, fears, concerns, etc.) in an unfair way
The company plays on [=takes advantage of] the concerns of parents in order to sell their products.
Politicians often win votes by playing on [=exploiting] people's emotions.