What is the ruling on playing a game that contains characters claiming to be gods, knowing in one's heart that they are not, and with the intention of playing with them as ordinary characters?

It is not permissible to play games that involve an affirmation or glorification of polytheism (shirk), even if the player denies it in their heart. The mere intention of the player that those who are called deities in the game are ordinary people does not make playing them permissible.