game over

1. A phrase used to indicate that a game, typically a video game, has ended because the player has lost. Wow, I remember that "Game Over" screen from playing this so often as a kid. No, no, no! Ugh, I tried to get her a potion, but I wasn't quick enough, and look—"Game Over." A: "'Game over,' huh?" B: "Yeah, I need to level up before I challenge this boss again."

2. By extension, a phrase used to describe a situation that has failed or is likely to fail. If we don't score another goal soon, it'll be game over. When she finds out you cheated on her, it'll be game over, dude. It was game over for Margaret when the company discovered she was embezzling money.

game over

said when a situation is regarded as hopeless or irreversible.

This expression probably comes from the use of the phrase at the conclusion of a computer game.

2001 Wall Street Journal There's a finite amount of money available, and, if it runs out, game over.