It starts early, it ends late, and if you go, you’ll probably lose your voice shouting along to “Killing in the Name” with a stranger.

Leftapalooza, Longmont’s rowdiest, rockiest, beer-soakiest music marathon, returns from 10:30 a.m. to 10 p.m. Saturday for a day of beer, nostalgia and tribute bands going mic-to-mic for a $1,000 prize and a shot at headlining next year.

The truth is, nobody is seeing Led Zeppelin live in 2025 unless we figure out how to resurrect John Bonham. And Rage Against the Machine had to cancel a reunion tour after Zack de la Rocha ruptured his Achilles. The gods of rock are aging (and in Bonham’s case, well, dead), but tribute bands are out here doing the heavy lifting, channeling the same ferocity, swagger and decibels — with zero orthopedic setbacks.

“People love tribute bands,” said Jill Preston, Director of Marketing at Left Hand Brewing. “I don’t know if it’s just a Longmont thing, but they really love coming out and singing along to their favorite bands from all different eras. This has become our most successful event. There’s a reason we’ve kept it going for nearly 15 years. It’s just a blast.”

Leftapalooza began with a simple idea and a few amps in the parking lot of Left Hand Brewing. Inspired by the rise of tribute bands and a cheeky nod to Lollapalooza, the team launched a local version that put cover acts center stage.

“We thought, ‘There are so many great tribute bands out there. Wouldn’t it be fun to have a tribute band competition?’” said Preston.

From there, the festival grew steadily, and after a several-year run at Roosevelt Park, it eventually found its perfect home in the brewery’s custom-built beer garden, at 1245 Boston Ave., directly east of the brewery’s tasting room, where fans can enjoy hours of live music just steps from the taps.

“We want people to come together and have a great time, but more importantly, every ticket sale helps support our foundation,” Preston said. “We’ve donated hundreds of thousands of dollars over the years to different local nonprofits, and we’re proud to keep giving back. So while it’s definitely a fun day of music and community, we’re also celebrating the impact we can make together.”

In 2015, Left Hand launched its nonprofit, Left Hand Brewing Foundation, an organization that collects funds to support community causes and groups. Tickets to Leftapalooza support the foundation — and the cover band event, along with LeftHand’s Oktoberfest, has become a fundraising engine for community impact. Last year, Leftapalooza raised $12,000 to be donated to The OUR Center in Longmont.

On Saturday, seven tribute bands will hit the stage, each cranking out their fiercest covers in a bid for crowd supremacy. It’s an all-day showdown where the audience decides who wins by casting votes throughout the day, giving the power squarely to the people.

Headlining the festival is Shotgun Opera, last year’s champion, returning with another hard-hitting Linkin Park set. Earlier in the day, Van Zeppelin takes on the impossible task of merging Led Zeppelin’s mysticism with Van Halen’s party-starting bravado. Guerilla Radio, a Rage Against the Machine tribute band, delivers politically charged anthems with full-throttle intensity. Other acts on the bill include Cold Replay (Coldplay), Live Wire (AC/DC), El Loco Fandango (ZZ Top), and Sabotage (Beastie Boys), offering plenty of chances to scream, sing along, or maybe do the worm.

Van Zeppelin might sound like a parody at first, but the Lafayette-based band takes its music seriously. When they’re not channeling the spirits of two of rock’s most iconic acts, the four musicians spend their time writing and performing original music in a heavy metal, funk, psychedelic-thrash project called Cönaxx.

“We never planned on being part of a tribute act,” said guitarist Anthony Manzanares. But during Cönaxx sets, the band would occasionally throw in a few Van Halen covers, which quickly became fan favorites. “A promoter we worked with regularly told us more than once, ‘You guys should do a Van Halen tribute band.’”

At first, the band — which also includes Dylan Montoya on drums, Alex Smith on vocals and Kenny Karsten on bass — kicked around the idea of going all in on Van Halen. Then, during a brainstorm, their singer blurted out, “What about if we went by ‘Van Zeppelin?’”

“As soon as he said it, we all stopped,” said Manzanares. “That was the moment where we knew we had something.”

The band leaned in, quickly realizing just how naturally the catalogs of Led Zeppelin and Van Halen could intertwine.

“A few of us had Van Halen as our No. 1 band growing up,” Manzanares said. “We all grew up on this music and already knew it really well.”

As they experimented, they found unexpected harmony between the two legacies: many of the songs were in the same key, and the lyrical themes (debauchery, rebellion, relationships, all laced with innuendo) complemented one another in surprisingly cohesive ways.

They built a 10-song set arranged like a chaotic mixtape: two Zeppelin songs, two Van Halen songs, and so on.

“It played like a shuffled playlist,” Manzanares said. “When we played it live, the transitions felt great, the energy flowed, and the crowd loved it. So we stuck with it.”

This year’s setlist includes what the band calls their most electrifying stretch: a 20-minute run of nonstop showmanship that kicks off with “Moby Dick,” where drummer Dylan Foos takes the spotlight, then tears into “Hot for Teacher,” “Eruption,” “Mean Street,” and, finally, a live-inspired version of “Dazed and Confused.”

“That whole sequence is full of musical fireworks,” said Manzanares. “We end it with ‘Dazed and Confused,’ which we perform slightly slower than the studio version, more like how

Zeppelin played it live.

“There’s a moment in that song where Jimmy Page used a cello bow on his guitar to create these wild, atmospheric sounds. We include that as well. It’s a trippy, immersive moment that really draws the crowd in.”

That balance of reverence and rawness is something Van Zeppelin has worked hard to strike. According to Manzanares, they stay true to the original material without sounding like a cover band on autopilot.

“When we learn a song, we start with the studio version to get the structure right,” he said. “Then we study live footage. Both Van Halen and Led Zeppelin often changed things up in concert. We want to capture that feeling.”

Also taking the stage on Saturday is Guerrilla Radio, a Rage Against the Machine tribute band built on fury and a whole lot of (guitar) feedback. Based in Colorado, the band plays with the kind of conviction that turns a cover set into a full-on call to action.

Guerrilla Radio has been around since 2011, originally started by guitarist Mike Shamrock out of a deep love for Rage Against the Machine. Vocalist Jeremy “JRock” Michael joined seven years ago and didn’t need much convincing.

“Rage doesn’t tour anymore, and in today’s climate, their music feels more important than ever,” Michael said. “They were putting out strong political messages and socially conscious lyrics that still need to be heard. All of us in the band love Rage, and we want to keep that message alive and loud, especially here in Colorado.”

The lineup includes Shamrock on guitar, Michael on vocals, Randy “Rambo” Maiz on drums, and Paul “Pauly C” Kelly on bass. The band’s goal is to capture the spirit and explosive intensity of Rage’s early days, and according to Michael, they’re not shy about letting loose.

“Someone once said we’re the four angriest white guys they’ve ever seen, which cracked me up,” he said. “We’re four white gringos who love playing Rage Against the Machine.”

Guerrilla Radio doesn’t hold back when it comes to live performances. The band thrives on big crowds and big energy, building each setlist to keep the momentum rolling and unrelenting.

“We’re going to bring the bangers,” said Michael. “For big festival crowds, we like to keep the energy high.”

This year, they’re throwing in a deep cut from Rage’s “Renegades” album that fans might not expect.

“‘I’m Housin’ is a cover of an old EPMD hip-hop track and it’s a classic,” he said. “Of course, we’ll play ‘Killing in the Name,’ too. That’s the anthem. Nothing beats seeing a crowd of people from all walks of life throwing their middle fingers up and yelling, ‘(Expletive) you, I won’t do what you tell me.’ That moment never gets old.”

Michael’s personal favorite to perform is “Wake Up,” the searing closer from “The Matrix” soundtrack.

“That’s always been my favorite Rage song to perform,” Michael said. “It’s still so relevant to what’s going on today. Rage was singing about this stuff back in the ‘90s, and it’s still happening, especially with everything going on in Los Angeles right now. Their album “The Battle of Los Angeles” hits differently in 2025, and Tom Morello is still out there protesting and holding signs, even though he’s getting older and can’t tour anymore because of his heel injury. I, myself, am 47 and people always ask me where I get the energy from. I don’t know either, but it’s there.”

Leftapalooza kicks off at 10:30 a.m. on Saturday, with music starting at 11:30 a.m. and continuing late into the evening. Fans can expect shaded seating, a fresh lineup of food trucks and an expanded beer selection featuring both Left Hand staples and pours from Dry Dock Brewing.

Kids ages 12 and under get in free, but dogs (service dogs allowed), canopy tents and large coolers should stay home. Parking across the street is $5. Tickets start at $22.58 with VIP packages also available, and proceeds from the festival will benefit the Left Hand Brewing Foundation.