Thousands of players have already logged miles on Zwift since the game's invite-only Beta program began last fall — and it's easy to see why. Zwift Island is more than a vacation from the gray and salty world of disgruntled motorists, crashes, and snow-covered bike lanes. It's really fun.

A lap around the island's 3-mile loop reveals a beautiful 3-D world seemingly inspired by many of the iconic places any cyclist would want to visit: Hawaii, California, Colorado, France. Riding clockwise, virtual cyclists depart what resembles a Portuguese fishing village of triple-decker cottages decorated with verandas and flags. The road opens to a tropical bay lined with palm trees and flowers. A blimp floats above a cruise ship as sounds of waves and seagulls play through the computer's speakers. As the road points upward, the tropics give way to a forest of California redwoods with crickets, squirrels, and an occasional deer. Green fireflies flicker about when pedaling up "Col du Zwift" at night. The ride finally plunges down a short, steep mountain descent with vistas that evoke Colorado or perhaps the snow-capped Alps in France. A volcano appears in the bay behind the last big turn in road.

The game includes many points of view, including first-person and another right behind the avatar.

What makes the game fun is that it appeals to a cyclist's competitive side and combines it with a social aspect. Once logged-in, Zwift cyclists can ride alone or join friends (or even the occasional pro such as Jens Voigt) and race them to the top of the mountain, for example, or simply try to beat their own best time. Players can also earn rewards like a new jersey or a bike for achievements like riding a century (cyclist-speak for "100 miles"), regardless of speed.

Tod Gentry, who lives in Boston and rides about fours a week on Zwift, says it has changed his training over the winter.

"Why does half of my training time have to be alone in a dark basement? Zwift takes what would be a lonely, two-hour tempo ride and connects you with a hundred other weirdos in basements," he said. "Having other cyclists on the island fills the competitive void that is otherwise missing on the trainer. . . . Watching other cyclists post faster King of the Mountain [times] or lap times stokes the competitive fire."

Zwift's creators plan a number of new features as they prepare to open the program to everyone in May, including more sophisticated maps, a workout mode, and a "Ride with Jens" event to promote the Tour of California. Later versions of the game might include organized races as often as every hour.

"We haven't even made it fun yet, that's the funny thing," said cofounder Eric Min.

Min added that his company is in the entertainment business and "we just happened to pick cycling because a bunch of us are passionate cyclists."

Between demand for the product (Zwift has received 40,000 Beta requests) and ever improving technology, the future seems wide open for the cycling game. Min said it might even be possible one day soon for Zwift cyclists to join actual races in real-time, including the ultimate ride: the Tour de France.

"Since early on people have been asking us, 'Hey we'd love to be able to do the Tour de France.' Because it's something they can't do in the real world. How fun would that be? I would pay for that kind of experience," Min said. (For now, Zwift is free, but the company plans to start charging in the fall.)

And for Boston Marathon athletes out there, Min didn't rule out a version of the game for runners.

"There's a huge opportunity [there]," he said. "What we're doing is changing the mind-set that indoor riding doesn't have to suck."

Ed Medina can be reached at joel.medina@globe.com. Follow him on Twitter @SurferMedina.