The biggest sensation of "Alien," the much-talked-about North Bergen High School play that got an encore performance Friday night, was not the flashing, rumbling special effects, the incredible sets made of flotsam and jetsam, the monsters popping out of chests, or even the alien itself, stalking people in the aisle seats.

The biggest sensation was Sigourney Weaver, in person — the star of the original 1979 movie "Alien," who made a special trip to North Bergen to give her blessing.

"How exciting is it to be here tonight?" Weaver said, before the curtain rose, as the overflow crowd of 800 in the school auditorium went wild.

As you probably know, this "Alien" became a viral sensation when someone posted video of the original performance in late March. The video got some 3 million hits — and the geek-o-sphere has been going crazy ever since.

"This is the night I've been waiting for!" Weaver told the crowd. "I've only been here a couple of hours, but I can tell this is a very special place in a very special town, and in a school like this you have extraordinary teachers…I met the students and I want to say they are so great."

Weaver's presence at what is — at the end of the day — a New Jersey high school play, suggests just how unusual the saga of this production is.

Also, how excited people have been since director-writer Perfecto Cuervo, who conceived what was supposed to be a one-off performance, announced earlier this month the encore staging Friday night.

There are other signs that this "Alien" is extraordinary. The fact, for starters, that Ridley Scott, the director of the 1979 film, donated $5,000 to the school after hearing about the show.

The fact that the New York Conservatory for Dramatic Arts has announced it is awarding $1,000 scholarships to all the cast and crew (a few will get $10,000 scholarships).

Marc Zicree, a writer who has worked on "Star Trek: The Next Generation," flew all the way from Los Angeles to see the production and cheer on the students. And Sam Mercer, of Vienna, Virginia, drove five hours to North Bergen to see it, not even knowing whether he could get a ticket (he snagged one at the last minute). "I didn't think I was going to get in until one minute before the play," he said.

The amazing thing about the show is not just the sophistication, the imagination, the technical brilliance of the show, but the fact that Cuervo, his team, and his actors made it out of almost nothing.

It was staged for a modest $3,500 (most big high school shows cost in the neighborhood of $20,000). The incredible-looking sets were made mostly from odds and ends. The fact that North Bergen High School doesn't even have a theater department speaks to the determination, resourcefulness, and sheer will of the students and faculty who were going to do this show, no matter what.

That's why the New York Conservatory is all in when it comes to these students. "We're trying to fund schools where the students really want to do this for a living, who are serious," said Bryce Russell, director of admissions for the New York Conservatory.

These students are serious, all right. The audience may have come just to wish a bunch of ambitious kids well. But as each expertly timed shock landed on cue, the audience laughed, cheered, and screamed, exactly as if they were at a professional Broadway play.

So is even this the end? What, after all, would "Alien" be without sequels?

There are no plans, Cuervo said, for more performances. But then again, with this play, there never are. "Formally, this is the last show," Cuervo said Friday night. "But we're definitely open to more."