Charles Swartz says he was looking for a fantasy tennis game to play last year and wasn’t satisfied with his options.

Professional tennis is pretty much a year-round sport (this year’s schedule runs from Jan. 4 to Nov. 29), and Swartz says that sometimes work keeps him too busy to stay on top of his fantasy team. So, rather than start one anyway and just let it go dead for stretches, he decided to launch his own fantasy tennis site.

After about six months of planning and development, GrandSlamFantasyTennis.com launched in beta in mid-January just in time for the 2009 Australian Open. That timing makes sense because — in case you didn’t gather it from the name — the site’s contests incorporate only the Grand Slam events: the French Open, Wimbledon and the U.S. Open, in addition to the Aussie.

“That’s how greatness is judged,” Swartz told FSB.com, pointing out that people recite the Slam titles for Pete Sampras and Roger Federer rather than the total tournaments won. “The idea that the fantasy tennis game revolves around that just made sense to me.”

The game is free and starts anew with each of the four events throughout the season. Participants can play the men’s side, the women’s side or both, building teams of eight players for whatever draw they choose. Scoring is based only on how far the chosen players advance. Users can’t pick more than five players among the top 16 seeds and must select one unseeded athlete. But that’s only half of the game.

In the other part, users predict the winners of every match from the fourth round on — with daily e-mail reminders making sure you don’t forget. Swartz says this component helps to keep the user engaged throughout the tournament, rather than merely setting a team of eight at the start and disappearing from the site. If a user isn’t available to make all of these picks, there’s a setting that will automatically choose the higher seed in each match for you.

No matter how big a fan of the Qatar ExxonMobil Open you might be, the Slam events clearly outdistance the rest of the schedule for exposure, drawing in even casual fans of the sport. The setup of Grand Slam Fantasy Tennis could further play into that casual-fan market.

“I wanted to create something that wouldn’t take a ton of time,” Swartz said. He added that the system of scoring wins and not other stats — in addition to broadening the game’s appeal — stays truer to tennis. “I didn’t want it based on stats. You can have great stats … and lose.”

The big challenge will be to keep users on the site in between the tournaments, which Swartz hopes to do with forums and the blog. He does, however, say that he envisions adding a longer game to the site that incorporates other tournaments and compiles fantasy stats throughout the year rather than treating each tourney separately.

In the long run, Swartz said he hopes to build to the point where he can align with tennis equipment companies, outfitters or other big-brand advertisers and offer large prizes. For anyone who might doubt the level of interest, he points to Roger Federer’s Facebook fan page — which as of Saturday evening boasted 1,827,419 followers.

By comparison, here are some other totals FSB.com came up with at the same time …

LeBron James — 585,299 fans

David Beckham — 1,406,191

Britney Spears — 1,558,288

American Idol — 556,229

In the meantime, Swartz says he’ll work on nailing down his ideal scoring system and adding features. The site is coming out of its beta phase for Wimbledon, which opens June 22.