May 24, 2010  -- Whoa. What a finale.

More than two-and-a-half hours after the epic battle between good and evil on "Lost" squared off for the final showdown, the fate of the Oceanic Flight 815 passengers was revealed.

Spoiler alert: This article contains information included in Sunday night's "Lost" finale.

As the six-year series closed, along with Jack's eye -- nice book-ending, producers -- we learn that the flash-sideways world we've delved into throughout most of the final season was a kind of limbo, or purgatory, until the survivors could be reunited one last time.

The general consensus across America in the moments after the credits rolled was a resounding "Wait ... what?"

Click HERE to watch the executive producers share their thoughts on the final episode with Diane Sawyer.

The series' final moments made it clear that Jack Shepherd had died on the island and reunited with his finally proud papa Christian. But the epilogue of the rest of the cast remained up for debate on the Internet this morning.

Some people believe all aboard Oceanic Flight 815 died when the plane broke apart over the Pacific and slammed into the island in pieces.

But faithful watchers will know this -- the island was real. Their adventures, the Others, the Dharma initiative, the mythology -- it was all real.

Sawyer, Kate and Claire made it off the island for good aboard the Ajira plane (accompanied by Miles, Lapidus and by the finally-aging Richard.) Hurley, Ben and Desmond stayed behind to protect the island.

Their fates will remain hidden, though we learn from the final gathering at the church that everyone eventually died, some before Jack, his father told him, and some a long time after.

Those who had previously died on the island -- Sun, Jin, Sayid, Shannon, Boone -- never got a second chance except in the afterlife.

And as the group gathered, both buoyed and amazed by the connections they remembered, they moved on together -- no longer stuck between worlds, able to finally find peace.

'Lost's' Mysteries: What Got Solved, What Will Remain Forever Hidden?

While dozens of questions about the series remain unanswered, we did get some closure with the characters' personal lives. Kate chose Jack in the hours before he died. Sawyer found Juliet, his true love, in purgatory. Ben finally accepted his place on the island as No. 2 -- a role he took on with honor after decades spent fighting for something more.

Last week, ABCNews.com questioned several longstanding mysteries on the "Lost" island. Below, we go back to find out what was solved and what remains up to the viewer to figure out.

'Lost' Numbers: 4 8 15 16 23 42

It's become common theory in the blogosphere that the meaning of the series of numbers, central to so many of the island's events, was never revealed.

The numbers -- used by Hurley to win the lottery and Desmond to keep the hatch from exploding -- have popped up dozens, perhaps hundreds, of times over the course of the show.

Producers used them almost as a "Where's Waldo" type of challenge for devoted Losties, sticking them on sports jerseys and bedside alarm clocks. They even served as the flight number for the doomed plane itself.

But did we really learn their significance? Probably not.

Smoke Monster Death: How to Guide

Sure, we found out how Jacob and the Man in Black (later to become the smoke monster) came to live on the island -- shocker, they're twins! -- when a recent episode revealed they had been born to a shipwrecked young mother and raised by an all-knowing woman who bashed the mother's head in shortly after she gave birth.

But when the young castaway questioned the island woman about where she came from, the woman simply brushed her off, saying, "Every question I answer will simply lead to another question."

It almost seemed to be a message from "Lost" producers, straight into the living rooms of the show's fans.

We never found out where Mother -- the woman who raised them -- wound up on the island or came to possess the power to protect it.

But as "Lost" ended, so did the epic battle between good and evil between Jacob and the Man in Black. Jacob faded as soon as Jack accepted his new role as island protector.

And Jack made good on his promise to kill the Man in Black inhabiting John Locke's body. Once Desmond extinguished the light, taking the Man in Black's powers along with it, Kate was able to shoot him in the back, followed by an assist over the cliff with Jack.

The only quibble with the finale? The Man in Black spent centuries trying to make it off the island, killing dozens and inspiring his twin brother to radically alter history for hundreds of people to keep him at bay.

And he's killed by a gunshot and a fall off the cliff. Seriously?

Desmond and the White Light

We've all known Desmond Hume was special from the very moment he came face to face with the survivors back in season one. And not just for his mega-watt grin and swoon-worthy accent.

Once the hatch-keeper, whose sole reason for existence was to push a button every 108 minutes -- there are those numbers again -- Desmond can withstand enormous quantities of the island's electromagnetic power even after others have died from the same exposure.

Charles Widmore, you know, before he was casually blown away by Ben, said Desmond was his "last resort."

And indeed, he was the last resort to saving the island from the Man in Black. It was Desmond's ability to withstand the electromagnetic energy to disable the island's powers long enough for the threat of evil to be extinguished.

Thanks, brutha. The universe owes you one.

Deep Sea Adventures

This season's opener introduced the flash sideways. Because, you know, after years of figuring out flashbacks and flash forwards, viewers needed a little shake-up.

But as we got to see glimpses of a world we don't yet understand, we were also treated to a very quick flash of the island in a flash-sideways world -- deep under the ocean with a Dharma-branded shark circling overhead.

It was referenced several times in the first hour when Fake Locke threatened to sink the island. And after Desmond removed the cork from the well of light, we did indeed see portions of the cliffs plummet into the ocean.

But we now know that the ocean floor island was part of the castaways' purgatory. So did the island sink when they finally moved on? We'll never know.

Shoes Off Everyone, Who's Got Four Toes?

Losties first got their glimpse of the giant four-toed statue watching over the island at the end of season two.

The statue in modern times is severed at the ankle, but flashbacks to the early Jacob days have included views of the back of the full statue. It appears to be an Egyptian god, the most popular theory that it's Sobek, a Nile god with the head of a crocodile.

It was revealed at the end of season five that Jacob lived inside the statue, but it was never revealed where it came from or why it watches over the island.

Where Did They Go? The Walt and Vincent Edition

The show relied heavily on Walt -- Michael's young son who was being brought back to live with his father after years of estrangement. When they crashed on Oceanic 815, they crashed along with Vincent, Walt's loyal yellow Labrador retriever.

Walt was supposed to have been special, to be able to do things and see things the others couldn't, including teleporting while being held hostage by the Others. But then his father took him off the island, and we saw little of him after that.

Michael ended blowing up along with Widmore's freighter -- can we call being blown up pulling an Arzt? But Walt hasn't been seen since a brief meeting with John Locke in season five's "Life and Death of Jeremy Bentham."

We never again saw Walt or Michael. Not in the flash-sideways world and not in the church. Could it be that Malcolm David Kelly, the actor who began playing young Walt at the tender age of 12, grew so much physically during the show's run that his character no longer fit -- literally -- into the story?

But we got lots of Vincent. After a brief appearance in season five under the care of time-traveling Rose and Bernard, we found that's where Oceanic Flight 815's only canine survivor has been all this time.

As a mortally wounded Jack crawled into the bamboo to die, the faithful Vincent laid by his side, just as he had in the moments after the plane crash six years ago.

Good boy, Vincent.

Richard Alpert: Smokey's Toss Can't Be the End

Oh, Richard. Oh, sweet, loyal, conflicted Richard. Rendered ageless by Jacob back in the days after Black Rock shipwrecked, Richard has formed alliances and dazzled us all with his naturally grown guy-liner.

We found out in the finale that the uber-gladiator toss inflicted by a really ticked off smoke monster didn't finish the old man off.

But curiously, once both Jacob and the Man in Black had died, Miles noticed a curious change in Richard: a grey hair. We'll take that to mean that Richard has finally been released from his lifelong sentence, free to leave the island after 150 years.