NORTH TONAWANDA — Almost six years, six seasons and more than 100 hours after “Lost” premiered Sept. 22, 2004, on ABC, only two episodes and 3 1/2 hours remain.

In a way, it’s amazing the show made it this far. In an era of reality television, how, exactly, do you easily define a twisting, turning, sci-fi-laced mystery with time travel and air of mythology to it?

Well, you don’t.

And that’s what makes it so incredible that “Lost” has collected such a vast and rabid legion of fans over the years.

Me, I like mysteries. I like sci-fi. And I like mythology. And I have to respect a show that’s had me reading up on Roman history, geography, geophysics and Egyptian mythology ... and that’s over the past four months alone.

After all that,  3 1/2 hours is a pretty narrow timeframe left for a show that’s thrived on the confusing and the obscure — and begs the question: How much will really be explained?

Since I’m writing this before the airing of episode No. 15, “Across the Sea” — in which a plethora of answers are said to be revealed — I’m going to stay away from one of the show’s long-running puzzles, the identity of the so-called “Adam and Eve” skeletons found in the caves during the season one episode “House of the Rising Sun.” In fact, I’m not even going to guess (though I have my suspicions).

It’s not like there’s a dearth of puzzles to choose from, after all.

So, here, in no particular order, are this writer’s top six remaining mysteries of “Lost.” Any answers forthcoming in Tuesday’s “Across the Sea” have not been taken into account.

• ONE: What’s going on with the so-called “flash sideways” timeline?

In the season six premiere, “LA X,” there was revealed to be a a divergent storyline running interspersed with the continuing on-island events.

In it, the original Oceanic Flight 815 lands safely in Los Angeles. The island is shown submerged in the ocean.

There are a number of other differences. Jack Shephard has a son. Sawyer is a cop. Hurley is lucky. You get the picture.

Since then, some “sideways” characters have become aware that something’s not quite right about their lives (and sometimes they’re helped to that realization). What will come of that remains to be seen.

Some people think it’s an epilogue to the events of the show. Some say a construct. Others, a different dimension of sorts. I’m going with construct. But by whom?

Another oddity: The timeline is shown running in 2004, as opposed as the on-island 2007 timeline. Why?

• TWO: What’s up with the creature in the guise of John Locke?

What seemed to be a fairly straightforward survival story changed abruptly during the “Lost” series premiere when the castaways were woken by loud noises and falling trees in the jungle. Not long after, before the eyes of other survivors, a black-smoke monster (for lack of a better description) pulls the pilot from the cockpit of the crashed plane ... and the man is later found dead.

Since then, it’s been seen a number of times in black-smoke form, responsible for the death of any number of characters. It’s been referred to by others variously in the know as a security system, or as “Cerberus.”

Since then, the black-smoke creature has appeared as a number of dead characters and, finally and memorably, in the guise of deceased main character John Locke in season five.

What’s he want, really? Who knows? Monster-as-Locke says he wants to get off the island and go home (wherever that is), but his actions mainly seem to be concerned with disposing of other characters.

His motives were expected to be revealed in “Across The Sea.” We’ll see. I can’t believe we’ll get the full story until at least the finale ... and maybe not even then.

• THREE: Who will replace Jacob? Or is that even the point?

Erstwhile island protector Jacob (Mark Pellegrino) met his death in season five finale, “The Incident,” killed by one-time Other leader Benjamin Linus — who was being manipulated by the aforementioned Smokey-as-Locke.

Since then, both Smokey and other characters have described a certain list of Flight 815 survivors as “candidates” ... apparently to replace Jacob as island protector (a written list — with many names crossed out — has actually been seen in a cave on the island and in the lighthouse ... but there’s not room to get into that here).

Among the list, which only includes last names: Shephard, Ford, Reyes, Jarrah and Kwon. With the recent deaths, that leaves only three candidates.

What makes a person a candidate? Why does a person get crossed off the list? And are they truly the options to replace Jacob, or something else entirely?

Smokey thinks so, apparently.

• FOUR: Who else is going to die?

The executive producers of “Lost,” Carlton Cuse and Damon Lindelof, have said the death toll in season six is going to climb.

Three main characters, ones who’ve been around since the pilot, died in the May 4 episode, “The Candidate.” Chances are more will certainly follow suit.

My bet: Charles Widmore and Ben Linus, possibly in the end of that complicated character’s redemption arc. And perhaps Sawyer, for similar reasons.

• FIVE: What’s the significance of Aaron? And what about Walt?

“Lost” has had a history of child characters described as “special.” Aaron, born on the island to Claire Littleton and now off island in the care of his grandmother, is one of them (Claire was warned by a psychic that she had to raise him herself but has not ... and that’s another story).

So is Walt Lloyd, a crash survivor at age 10 and son of crash survivor Michael, now off the island? Walt has exhibited odd powers and was once kidnapped by the island “Others” for mysterious reasons that still aren’t clear.

It’s anyone’s guess if the children will have some sort of significance in the end of the show, or the “game” between Jacob and Smokey.  My guess: Yes, at least Aaron.

• SIX: Who does Kate Austen (Evangeline Lilly) end up with?

My research online has convinced me that, yes, people really do care about this. Personally, after six years of the Sawyer-vs.-Jack thing, I’d rather like to see Kate Austen walk off into the sunset on her own, an independent woman with more important things to worry about.

Sorry, ’shippers.