Considering Chicken Invaders Universe isn’t a campaign/arcade-style game and there’s very little consequence for failure, “Game Over” doesn’t really fit anymore. Yes, it fits in the sense that you lost all your lives, but considering the game is made up of player-selected missions instead of a predetermined sequence of them (and since the game doesn’t boot you to the main menu upon losing), “Mission Failed” would be much more appropriate.
I vote that “Game Over” is kept due to hiﬅorical reaſons and becauſe “Miſſion Failed” ſounds a lot more negative.
Here’s another suggestion:
Better luck next time!