ˈball game noun [countable]1. American English a game of baseball, football, or
basketball2. British English any game played with a ball
3. a whole new ball game a situation that is very different from the one you are used to:
I used to be a teacher, so working in an office is a whole new ball game. [TahlilGaran] Dictionary of Contemporary English ▲
ball game n.,
slang, also
informal The entire matter at hand; the whole situation; the entire contest.
You said we can get a second mortgage for the house?! Wow! That's a whole new ball game. [TahlilGaran] English Idioms Dictionary ▲