Fox
It ended with a brilliant play by quarterback
After a pass to Calvin Johnson got the Lions down to the one-yard line with no timeouts and 15 seconds left, Stafford run up to the line and acted like he was going to spike the ball.
Even his teammates appeared to think it was going to spike (notice how the lineman just stand up straight after the snap, and the receivers don't even move).
But instead he jumped over the pile for the game-winning touchdown.
Here's the play:
Fox
And a close-up of Stafford telling everyone it's going to be a spike (pointing to the ground is the accepted symbol for spike), via BuzzFeedSports:
Calvin Johnson had 329 receiving yards in this game. But it was Stafford's improvisation at the end that got Detroit the win. If he doesn't get into the endzone here, there's a chance the clock runs out before they can run another play.
The Cowboys had a 99% win probability with 1:24 left (via @xmasape):