Wikipedia's list of sports has (at the time of this writing) over 400 entries. This falls woefully short of covering all the numberless types of organized physical competition. Turning them all into computer games will take decades, assuming anyone considers that, you know, worthwhile.
Someone probably does. Someone out there must want to bring out a PC or console version of, say, takraw/chinlon (kick volleyball), chess boxing or dwarf tossing. How can we know this? Because of all the offbeat sports someone already turned into computer games.
By "offbeat," mind you, we're not talking about sports known worldwide except to parochial North Americans, like cricket (seen in Cricket Manager, among many others) or rugby. Nor do we mean sports that once seemed odd subjects for computer games, until someone figured them out. Hunting, for instance - no one predicted the tremendous success of Deer Hunter in 1997, but now it has platoons of imitators. Hunting games are "offbeat" only in that they come from non-game publishers. For instance, the outfitting chain Cabela's sells Cabela's Big Game Hunter Alaskan Adventure, African Safari, Outdoor Adventures, Alaskan Adventures, Cabela's Dangerous Hunts 2, Ultimate Duck Hunting 3D, Daisy Air Gun Fun and the ominous-sounding Hunter Dan Bowfishing Survival Gauntlet. (Cabela also sells a Laser Shot Technologies Home Theater Shooting Simulator. Buddy, if you're about to spring $3,000 for that toy, consider going outside and talking to a real girl.)
Likewise, no one raises an eyebrow about all the fishing games; nor extreme motocross, snowboarding, etc.; nor volleyball - though it's unclear how important volleyball, the sport, is to the sun-bleached Dead or Alive XTreme Beach Volleyball, with its anime bikini-babe jiggle physics. (It's not an accident the game can be played one-handed. Ewww.)
Perhaps we can define "offbeat" as "not published by Electronic Arts" or "not covered on mainstream sites like Sportsology." More seriously, these are sports you just can't picture as computer games, like yachting, kite surfing and water skiing, to mention a few.
In fact, all these have already been adapted. Can dwarf tossing be far behind?
There used to be many games about unusual sports, like 1999's Professional Bull Rider and ultralight flight simulator Hangsim. But as production costs rose and publishers focused solely on the mass market, these games got forced off retail shelves. They went indie, moved onto the web and found a different audience. Today, these sports games emphasize simulation over gameplay. Their customers are not so much gamers as sports fans. Some sims explicitly pitch themselves as good training for the real activities, in the manner of the X-Plane flight simulator and the Virtual Air Traffic Flight Simulator Network.
So, for instance, Joey Skinner of Rodeo Software has made a nice business selling computer games for horse people, such as TRSim (Team Roping Simulator), BarrelSim (barrel-racing), and TDRSim (Tie-Down Roping). Rodeo's RopingArena.com has nearly 13,000 registered players. Its Year-End World Finals for 2005 offered $2,500 in prizes from sponsor Sparky Superior Roping Machines, maker of Sparky III, "the first and only functional ground-driven team roping machine." In the December 2005 RopingArena newsletter, Skinner interviewed Bret Trenary, an award-winning roper with 35 years of experience. "You can play on the simulator, and then go rope real steers, and I think you are actually seeing the same look on both runs," says Trenary. "I think real-life roping is mostly hand-eye coordination; what better way to work on this than on a simulation you can do over and over again. There are people around here who have played and actually figured out how to score steers from this game. It is a really awesome concept."