Game Over is when a minigame ends. In games with no victory-system (goes endlessly until you lose and in some minigames, it gets harder the more you play), an end screen will appear to the player, typed Game Over and the reason of why the game ended. The reason will depend, since it can be changed due to the form that the game ended.
An additional sound will play when the Game Over screen appears to the player.
When Pou gets stuck on the platforms, leaving no room to fall.
Time's up!
It happens when the minigames have a timer. The direction and color may vary. When the timer runs out, the Game Over message "Time's up!" will appear on the screen.
There are some minigames with different gameplay modes. As a result, the Game Over messages are unique. These messages can be "You win!, as well as "You lose!". These are the minigames in which it's possible to win or lose a match.
When the opposing Account beats you. In online matches, the message is different to the "You lose!" message. The message for these games is the opponent's name + "wins!" instead (for example: Pouwins!). Read more about PvP mode.
There are two minigames that don't have game-end screens: Pool and Goal. These minigames are from the Outside location. When the player loses, the score number simply resets without an end screen.