Does saying, "I struck him a blow that knocked him off the Throne," in the context of joking and favoring one person over another in a game, constitute polytheism (shirk), given the speaker's ignorance at the time of the great meaning of the Throne and his deep remorse?

The statement, "I struck him a blow that knocked him off the throne," made in the context of play, is permissible. This is because a throne can be attributed to a created being, both literally and figuratively, as in Allah's (the Most High) saying about Yusuf (peace be upon him): "And he raised his parents upon the throne" (Quran 12:100), and His saying about Bilqis: "And she had a mighty throne" (Quran 27:23). The expression "he ascended the throne of the game" is a metaphorical idiom meaning progress and excellence in it, and it has no relation to the Mighty Throne of the Most Merciful. It is advised to beware of obsessive doubts in this regard.