Here's what happens:
* Adam (the protagonist) escapes the bathroom trap. He manages to free himself from the chains and, with a broken leg, crawls to safety.
* John Kramer (Jigsaw) reveals himself. Adam finds a video tape revealing that John was actually the mastermind behind the entire ordeal. He reveals he did it because he believes people have lost their appreciation for life and need to be "tested."
* The twist: John reveals he was also trapped in the bathroom with Adam. He was the one who orchestrated the whole thing to make Adam "earn" his life.
* John dies: The ending shows John dying from his own trap, a reverse bear trap that crushes his skull.
* Adam is left alive. He escapes, but the experience has clearly left a lasting impact on him.
The ending leaves a lot open to interpretation:
* Did Adam actually "earn" his life? This is a question the film leaves unanswered.
* Is Jigsaw truly dead? While we see him die, some argue that he could have staged it.
* What will happen to Adam now? The ending suggests he's going to be haunted by the experience.
The ending of *Saw* is both shocking and thought-provoking. It leaves viewers questioning the nature of life, death, and the meaning of survival. It also sets up the rest of the franchise, which explores the complex morality and legacy of John Kramer's "games."