12 Hours (itch)

20 years ago the world was on the brink of nuclear war. Out of fear, your country armed their weapons with a dead man's switch. At a remote facility, a terminal was set to require a biological override every 12 hours. Should the input not be received the terminal would set the weapons to launch. In the twenty years between then and now, those that built the system died, along with 90 percent of the human population. The scattered remnants of humanity are trying to rebuild as you watch from the terminal. They know nothing of the weapons below their feet, the weapons that are never more than 12 hours away from destroying the last of the human race. The only thing between them and destruction is you. Every 12 hours the terminal requires input. Until you draw your last breath, you intend to provide it.