Game Over is a message in video games which signals that the game has ended, often due to a negative outcome - although the phrase sometimes follows the end credits after successful completion of a game. In certain uses; particularly during conversation, Game Over is sometimes shortened to the first two letters: GO with each letter pronounced individually G O.

The phrase was used as early as the 1950s in devices such as electromechanical pinball machines, which would light up the phrase with a lamp (lightbulb).

Before the advent of video game consoles and personal computing, arcades were the predominant platform for playing games which required users to deposit a token or coin (traditionally a quarter, in the U.S) into an arcade game machine in order to play. Players would usually be given a finite number of lives (or attempts) to progress through the game which when expended would usually result in the display of the message "Game Over" indicating that the game had ended. The phrase might also be followed by the message "Continue?" and a prompt asking the player to insert additional tokens to prevent the game from terminating and allowing the player to continue their progress. As these games were ported to home consoles, the "Game Over" screen and "Continue?" prompt remained, but often required only the press of a button to keep the game going. While the video game industry slowly shifted away from being arcade-focused to being home gaming-focused, the need for a "Game Over screen" gradually lessened as there no longer had to be a system in place to get additional money from the player. However, the concept of Game Over still remained a gaming staple for many years to come, not as a way to empty players' wallets but to add an element of risk to gaming: If the player doesn't do well and they eventually run out of lives and their game is over, they have to begin again from the start. Thus, avoiding the Game Over screen was preferable.