There's a different layout on the title screen/main menu for every chapter. If you exit the game during a chapter, the corresponding layout will be there.
The time of day in the main menu matches the time of day in the chapter, and the city eventually changes in the background. The flag also gets progressively more tattered. The wailing guitar rendition of the USA national anthem gets progressively more distorted (as though the person playing the guitar was slowly losing their mind).
The sniper is initially not present, then appears, and is seen sitting back and relaxing, then sighting down his rifle at the city. He is then gone, then back with firewood for his overnight fire. He continues to hang around, then has another fire the next night.
Meanwhile, the two largest and nearest towers are set on fire to mirror the events of the 'Rooftops' chapter.
Next, those fires worsen and the sniper is found dead, with two ravens picking at his corpse. The flag is nearly in tatters and the music is mostly sour screeching with the near-final notes of the Star-Spangled Banner being choked out intermittently.
Finally, the towers have collapsed, the flag has fallen and the sniper's body is entirely gone.
I wish there was just feedback or a dead audio hum, but I think it's actually just more really screwed end of the national anthem, perhaps the same bits from the previous main menu layout.