A good time was had by all at iHeart

You were having the time of your life and you were lucky just to be there.

Of this, you were reminded.

Over and over and over.

It was like getting relentlessly flogged by your obvious good fortune, put in a chokehold by a four-leaf clover.

The iHeartRadio music festival, which returned to the MGM Grand Garden on Friday for the first of two shows, is a big deal.

You will forget the name of your firstborn child before event organizers and the performers themselves let you forget that.

On opening night, close to a dozen prime movers in pop, rock, country, hip-hop and electronic dance music came together for a concert that spanned more than five hours, with a rotating stage that allowed one artist to set up while another performed, so the music was nearly continuous throughout.

The show was broadcast on hundreds of radio stations worldwide — it will also be shown on the CW Network on Sept. 30 and Oct. 1 — and each act was introduced by a celebrity or some approximation thereof, from the omnipresent Ryan Seacrest to Kate Hudson to one of the whisker farmers from “Duck Dynasty.”

Fans were urged again and again to tweet photos and their enraptured, exclamation point-heavy assessments of the show, some of which were scrolled beneath two large video screens that buttressed the stage, which also displayed the many tweets from fans listening at home, bemoaning the fact that they weren’t present.

Frankly, you should feel blessed just to be reading about it after the fact.

The artists, too, seemed happy to be a part of it all.

Before each act performed, a brief video interview was shown where they sung the praises of the event and the opportunity to rub elbows with the other musicians, some of which took place on stage.

Rapper J. Cole, who turned in an equally conscientious and cocksure set, celebrating his rise to success while also acknowledging its drawbacks by pretending to strangle himself with his gold chain at one point, brought out R&B futurist Miguel for “Power Trip” and then performed his current hit “Crooked Smile” with TLC’s Tionne “T-Boz” Watkins and Rozonda “Chilli” Thomas.

Katy Perry was joined by rapper Juicy J who rhymed his verse on Perry’s minimalist, vaguely menacing “Dark Horse,” which adopts the torso-numbing bass levels of trap music and was a jarring tonal shift in Perry’s otherwise chirpy, frolicsome set, where she skipped rope, blew confetti at the crowd and gave brassy voice to a series of pop pep talks.

Next, members of pop rockers fun., bubbly as a carbonated beverage, joined Queen with Adam Lambert for “Somebody to Love” and “Fat Bottomed Girls” during the latter’s show-closing performance. Fun. singer Nate Ruess looked like a kid whose Christmas wish had just been granted as he fired his voice across the bow of Brian May’s battleship-sized guitar riffs.

Speaking of six-string ostentation, there was Keith Urban, who had a camera mounted to the head of his guitar for a better view of his prodigious playing. He sucked in his cheeks as he unleashed a swirling, tornado of notes during the lead to “Stars Fall For You,” later adding more longing than his words could convey during an expressive, yearning solo on “Stupid Boy.”

Urban’s set was loud.

The band who followed him, Muse, proved louder still.

The British bombast fetishists alternated the Prince-on-performance-enhancing-substances electro funk of more recent singles “Madness” and “Panic Station” with the amps-to-eleven rush of early fan favorites “Starlight” and “Knights of Cydonia,” which ended their performance with the rising volume of an airliner roaring down the runway en route to liftoff.

The crowd, which was a pretty even mix of 20-somethings and those old enough to be their parents, applauded Muse politely, without a tremendous amount of enthusiasm, giving a similar reception to short sets by EDM superstars Tiesto and Benny Benassi, who performed atop an L.E.D.-enhanced DJ tower at the back of the arena.

They awoke for Elton John, however, who earned the most impassioned response of the evening, even if not everyone seemed entirely familiar with who he was, exactly.

“This dude is awesome!” one younger audience member’s tweet read on the stage screens.

John savored the moment to the extent that he was practically licking it from his fingers afterwards, bobbing up and down at his lustrous red piano like a buoy in stormy waters.

His five-song set mostly consisted of jukebox staples as iconic as his sparkly stag garb, save for one, new song “Home Again,” from his latest album “The Diving Board,” John’s 30th.

It wasn’t as familiar to the audience members, some of whom sat back down after rising to their feet when he took to the stage, but it was a standout nonetheless, a spare, simply arranged torch song, equally cutting and contemplative, where John confronts the tension between looking back on his life while simultaneously attempting to keep moving forward.

“I’m counting on a memory to get me out of here,” he sang during the song’s opening verse.

Memories, nostalgia, are what big, fat retirement accounts are made of for an artist with as many past hits as John has charted.

It’s a credit to him, then, that he’s still capable of creating new ones, with fresh meaning, as he did on this night.

Contact reporter Jason Bracelin at jbracelin@reviewjournal.com or 702-383-0476. Follow @JasonBracelin on Twitter.