your/somebody's game

(one's) game

One's agenda, plan, or ulterior motive. I can't figure out why Janet is suddenly volunteering for the position she said she would never do. What's her game? Ah, so that's their game: buy up all the competition and then raise prices however high they want.
See also: game
Farlex Dictionary of Idioms.

your/somebody’s (little) ˈgame

(informal) your/somebody’s trick, plan or intention: So that’s your little game — getting me moved to a different office and then doing my job for me.
See also: game
Farlex Partner Idioms Dictionary
See also:
  • (one's) game
  • a hidden agenda
  • a change of heart
  • a mystery to (one)
  • appear to
  • be (on) the wrong side of (an age)
  • be on the right/wrong side of 40, 50, etc.
  • a turn of phrase
  • able to do
  • able to do it