When you have no good video games to play at a certain time. Whether if it's you've beaten every game you have, or if you're just over all of them.
GUY 1: "uh, I'm so bored right now, I wish i wasn't game dead"
GUY 1: "dude, why aren't you ever online anymore?"
GUY 2: "I'm game dead, there's nothing to play."