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A-Game
1. The highest stakes ring game that is available in a casino or cardroom. The opposite of the Z-Game.
"I can't even cover the middle limit with my cash. I don't even think of sitting down at an A-Game."

2. A player’s most focused and skillful play; their peak performance.
"The competition wasn’t easy, but I played my A-game and picked up some hands."

3. The variation of poker at which a player is most capable.
"I like Hold'em, but 7 Card Stud is my A-game."
 
Australian Poker Weekly