That was the last sound that Luke Smith, one of the three non-Dalek lifeforms left in existence heard before he died, shot down by a random Dalek. He had left the other two, the TARDIS and Captain Jack Harkness, a man who couldn't die, in order to get some air. It was stupid, and ultimately fatal, but he had needed space, so he went out and he died, three days before the sixth anniversary of his rescue from the Bane by Sarah Jane Smith, who had died heroically alongside The Doctor, Martha Jones, Clyde Langer, and Rhys and Gwen whose surname he didn't know, trying to save everyone, but failing.
The Daleks had then Exterminated every living thing living in all creation, but he and Jack had escaped in the TARDIS. That was two months ago. Since then they'd discovered that anything beyond the lifeless Multiverse of the Daleks was Timelocked and impossible to reach even with the Doctor's Timeship. Now as Luke went into the Darkness, he saw that Jack witnessed his death and was now running back to the TARDIS, that when he got there all he would see would be fifty Daleks destroying the last remains of Gallifrey. And then it was all over, and he went into the Darkness.
The Daleks couldn't kill Jack, but they could contain him in concrete, as others had in the past. And they did. There was no Ianto or anyone else to rescue him this time. As long as the concrete stayed intact, he couldn't come back to life. The Daleks had truly won.
Years passed. Centuries. The Daleks, being a warful race, ended up Exterminating each other in conflicts that made The Last Great Time War look like a schoolyard catfight. Finally there were only two Daleks left. After a long silence, one Dalek spoke.
"DO YOU WANT TO PL-AY CH-ESS?"
"OH-KAY. LOO-SER GETS EX-TER-MIN-ATE-D!!"
And so they played.
Centuries later, the loser was indeed Exterminated. The other then had no purpose, and initiated it's self-destruct seqence. The Multiverse was then completely lifeless.
What a pointless piece of writing, such utter crap. I'm amazed you've read this far. Gotta go. Bye. The End.
That's it. It's over. Go home. Go.