What’s somebody’s/your game?
Definition 1 of 1
Pro Tip 1/3Suspicion Implied
The phrase implies you suspect someone's motives. It's often used when questioning someone's sincerity or actions. 
When you started volunteering just before the election, it made me wonder, what's your game?
Pro Tip 2/3Colloquial Use
It's casual language, used more in speaking than in formal writing. Best for informal conversations. 
During the casual meeting with the new member, Lisa asked, 'So, what's your game here?'
Pro Tip 3/3Cultural Variance
Understand that the meaning can alter slightly between UK and US usage but general suspicious connotation remains. 
John's approach was different in the UK; he was often asked, 'What's your game, mate?'