After 29 seasons, two dozen countries visited, and almost 20 years on air, MTV’s reality competition series “The Challenge” is about to debut its biggest season ever. Hot off the heels of a charity edition, “The Challenge XXX: Dirty 30” not only features more players than ever before, but also boasts a $1 million prize for the first time in the show’s history. Nina Diaz, Head of Unscripted at MTV and VH1, tells Variety that “it was only fitting that we up the ante and put the biggest bounty in franchise history on the line” at this time in the show’s history. “Together with Bunim/Murray Productions, we wanted to do something extra special to celebrate this huge milestone of 30 seasons on air. BMP came up with incredible creative to take ‘The Challenge’ to new heights,” Diaz says.

But while it might seem like the super-sized payday begat the large cast, contestants were actually kept in the dark about just how much money was waiting for them at the finish line.

Contestant Veronica Portillo tells Variety that during filming, the contestants would discuss how other, newer MTV shows had larger cash prizes than their physically demanding one. “It would have been a completely different game had that information been told to everybody at the beginning,” she says. “People almost kill each other over the chance of splitting $300,000! It would have pushed people to other limits than the show has ever seen before.”

But series executive producer Jonathan Murray believes that the money isn’t the driving force for most of his players. “They do get compensated just for showing up, and the longer they last, the more they get compensated, but I think it’s really more about the experience,” Murray says. “It’s pretty cool to be thrown together with a group of people who you’ve sort of grown up with over the years. It’s like going to a college reunion.”

Formerly called “The Real World/Road Rules Challenge,” the show see MTV’s reality stars battling each other in physical and mental events ranging from endurance contests to hand-to-hand combat to puzzle solving. Former “Road Rules” contestants still continue to appear alongside cast members from “The Real World,” but in recent years, “The Challenge” began tapping talent from MTV’s dating shows like “Are You The One?” to fill out its roster.

“Dirty 30” is poised to present not only the “most scheming, conniving, clever” cast members the show has seen, per executive producer Scott Freeman, but also a diverse sampling of seasons past. “Challenge” staples Johnny “Bananas” Devenanzio, Jenna Compono, and Camila Nakagawa are once again competing alongside more recent returnee Chris “CT” Tamburello, while Portillo and Derrick Kosinki, two fan favorites who haven’t seen a “Challenge” in over 10 seasons, are both back to show they still have what it takes.

“When I was 19 I found the perfect job: It was competition, a fun social life, go watch yourself kick some a– on TV,” Kosinski tells Variety. “It was a match made in heaven for me.”

Contestants like Portillo and Kosinski faced the added challenge from being away away for so long: they didn’t necessarily know the politics of the more recent players.

“It’s kind of like I was a rookie [too],” says Portillo. “There’s these people that play all of the time. I didn’t have relationships with many people, and I also didn’t know the dynamics of relationships of the core group — of what they had been through.”

While Murray and Freeman can’t predict what drama their cast will deliver season after season (“The show’s a continuing soap opera,” Murray says), one area they can ensure continues to raise the stakes is the challenge events themselves.

“I used to describe it as like ‘X-Men.’ They put us out on this island in the middle of nowhere and they have us battle against each other with our own superpowers,” says Kosinski. “The best athlete doesn’t always win.”

Murray and Freeman work hard to throw them the contestant curves — for example, changing up the challenge schedule so that they have to compete the morning after their first night in the house, as well as with the addition of “Redemption House,” a competition within the competition that allows previously eliminated players a chance to get back in the game.

Though a similar idea was explored digitally during the “Battle of the Exes II” season, producers wanted to step it up for “Dirty 30.”

“It works perfectly because they just didn’t see this coming,” Freeman says of the idea for the redemption house. “All of a sudden they’re showing up, and they’re like, ‘Why are there still cameras on me?’ It was such a season full of so many wonderful people, we were sort of greedy; we didn’t want to let them go! So we got to keep them around and have the audience have more fun with them.”

“Dirty 30” is set in Cartagena, Colombia, and in the premiere episode, contestants battle it out in a multi-part race around a fort that was built in the 1600s. “With 29 seasons preceding this, we were able to go back and look at some of the ones that were so good to look at the elements of why and design a new challenge that hopefully results in the same kind of excitement and drama — but maybe in a different way,” Murray says. “The layout of the fort in Cartagena was something that we had been wanting to do with the challenge for quite a while. There were just so many things we could take advantage of in a historic city like that to help make ‘The Challenge’ feel bigger, too.”

“The Challenge XXX: Dirty 30” premieres on MTV Tuesday, July 18 at 9pm.