game-changer

cliché That which dramatically or fundamentally alters a situation or the way in which something is done or thought about. Their new smartphone is a complete game-changer. No one will be able to go back to the old design after this. This legislation has the potential to be a real game-changer for the country's tax code. White noise has been a game-changer for us. It's the only thing that gets the baby to sleep through the night.