Fremont Street Experience, a pedestrian attraction in downtown Las Vegas, put up a zip line to amuse patrons. It was supposed to last three months, and two years later it was still going strong.

"We had folks waiting in line for up to two hours," said Jeff Victor, Fremont’s president, who decided it was time to put up a permanent attraction that could handle higher volume.

Victor turned to Skyline Eco-Adventures of Puka­lani, Maui, a pioneer in zip line tours that skim over rain forests and fly past waterfalls.

Skyline helped assemble a team of amusement industry professionals that came up with something completely different. Dubbed "SlotZilla," the 120-foot-tall tower will be shaped like a slot machine. Instead of dispensing cash, it will launch riders onto zip lines.

Due to open in June, SlotZilla will have four side-by-side zip lines on two levels. Riders on the lower tier will be in standard seated harnesses, while on the upper level, riders will fly in superhero position along a 1,700-foot line down to Main Street.

Unlike standard zip lines, which rely on gravity, SlotZilla will launch riders on the top tier with a propulsion system that sends them off at 35 mph.

"We know that gravity will get you there, but we thought it would be a lot more fun if we got you there in a very different way," Victor said. "This helps ensure it’s thrilling."