THWACK - thump! That first sound is a well-struck drive - in this case, golfer Mike Rus' shot off the first tee at the Red Rock Valley Golf Course. The second? His ball smacking a canvas-covered projection screen 10 feet away. While Rus' real shot falls lifeless at the wall, his virtual drive shoots skyward, on the projected fairway in front of us.

"We have sensors, every few inches, that calculate shot speed and trajectory," he says. Those calculations send Rus' drive over a line of tall trees, bouncing toward the projected green. Tracking numbers spin in the display until his ball rolls to stop at the edge of the fairway. "You can see I hit it 212 yards," Rus says. An amazing feat, since we're standing in a computer bay 20 feet deep. "That's the ball speed off the tee," he says, pointing to the display, which also measured club speed and launch angle, "... and that's the distance remaining to the hole."

Mark Twain called golf "a good walk spoiled." It's hard to say what he'd say about virtual golf. There's no walk to spoil. It's a strange collision of stroke and science that challenges your focus, analyzes your game and never sends you farther than the nearest restroom.

PIXILLATED PUTTING

Rus is owner and general manager of Crosswoods Indoor Golf Center, a blockish beige Gilbert facility where hundreds of virtual courses converge. The interior, trimmed in dark wood and forest green, resembles a high end pro shop, with leather chairs surrounding a flat screen television in the center. But the walls are lined with video bays, each about the size of a shallow carport. From inside, repeated "THWACK - thumps" can be heard.

"You have to adjust to hitting inside," Rus says, as a duo across the room tee off. "First-timers can be a little gun-shy about letting 'er rip." The tee shots sound like golf, but the amenities feel more like billiards or bowling. Pub tables and stools dot the mouth of each bay. Players can drink or dine between shots. Shoe-leather strain is minimal. That, alone, can be a draw.

"Some of our customers have physical handicaps," Rus says. "Maybe they still like to golf but they can't do all the walking. We have clients with skin cancer, who can't be outside for so long. And some with sight issues, who can't follow the flight of the ball." Those struck ill by time and money issues can find comfort, as well. "Eighteen holes here will take about an hour, and cost you about $25, which is about your average off-season rate."

The sensors are depressingly accurate. My "Hong Kong slice" (which sends every drive toward China) shows up on the virtual course, too. But the sensor numbers help me slow down club speed until my drives straighten out. "We also do instruction here. It's a good place to break down your game," Rus says. A series of laser-straight, 50-foot drives finally put me on the green, grateful that virtual golf courses never get dark. Crosshatched grids chart the break of the green, and my putt finds the hole with the same hollow, draining sound that is every golfer's reward.

DIGITAL DO-OVERS

Golf - virtual or otherwise - is steeped in tradition. Rus says that's why his target market is cautious. "It is very different for first-timers. People come in, and they're not sure what to make of it."

Crosswoods' Gilbert center has been open for a year and a half. A second location, based in Chandler and focusing on corporate clients, is scheduled to open later this month. Virtual golf has come slowly to Arizona. "It's been very popular in the Czech Republic and in China," Rus says. Compact countries, like Japan, have also pursued the technology. "We have 15 to 20 courses in this country," he says, "but most of them are centered in the Northeast and Midwest."

Virtual golf has its shortcomings, too. "You don't get the fresh air, or the same amount of exercise," Rus concedes. Changing ground (fairway, rough, putting green or bunker sand) is approximated with different hitting textures on the tee area. "But you're playing under climate control, 10 feet from college football games (on the television)." In real life, playing the historic St. Andrews course means a hefty airfare to Scotland. In virtual golf, you go to the menu screen, scroll through the 36-course repertoire, and ... hoot man, tee off.

Rus doesn't see virtual courses ever replacing real ones. "Our peak season is actually the summer months, when people are looking to escape the heat. But we also see a spike in the winter, when outdoor courses charge a premium." Virtual golf works well as an instructional tool, and an adjunct to outdoor play. "Arizona has a lot of golf course options to choose from. But we do have a place in the market. We're an economically viable option, and a good choice when you're pressed for time and want to get 18 holes in before dinner."

My chip shot reaches the green, passes the green, and burrows into the rough on the far side.

"Want to take a mulligan?" Rus asks. "There's a button for that."

Oh, I'm sold.