The virtual obstacle course of Sky Challenge
While most massively multiplayer online games (MMOs) are based on fantasy worlds, there is a growing trend for a new kind of game that merges the real world with the virtual.
Rather than taking on the persona of a mythical character who goes on quests, players of this new breed of game compete against one another in real sports, based in the real world.
At first glance, these games resemble racing simulations, but - with unparalleled realism and the ability to race against a large number of people, including professionals - they represent a cut above the rest.
iRacing is an internet-based auto racing simulation system in which drivers can race against dozens of other online participants on race tracks modelled on the real thing. This is the latest offering from Dave Kaemmer, who is responsible for other racing simulation video game titles including NASCAR Racing.
But the makers of iRacing are keen to stress that it's more than just a game. "We call it a massively multiparticipant internet sport," said Mr Kaemmer, CEO of iRacing.com Motorsport Simulations.
"Games have a short lifespan because people don't find them to be compelling in the long term. This is a way for people to start to do this kind of more serious activity online."
Online racing tracks are true to the real thing thanks to laser scanning
iRacing uses laser-scanning technology to accurately replicate real racetracks, while vehicle-handling dynamics are reproduced using a physics engine and tire model so that each car feels different to drive.
"We reproduce the surface of the racetrack to within millimetres of the actual circuit. When you are out driving on it the car is going over the same bumps, its got exactly the same road cambers and elevations and, visually, it looks the same," said Mr Kaemmer.
Sky Challenge takes this link to reality a step further, allowing players to race against real jets. High-performance aircraft race through a virtual computer-generated obstacle course in the sky. The course is stored in onboard computers and the pilots flying the planes see the series of animated objects through which they must fly on a small screen display.
"The same course is stored in ground based computers, along with the live position of the racing aircraft. This means internet gamers can join in the action, in real time, by connecting to the ground computer system. They fly through the same virtual course - at the same time as the real aircraft," Peter Newport, CEO of Air Sports Ltd. who developed Sky Challenge, told the BBC.
The course is also dynamic. It can adjust to punish or reward competitors for penalties and bonuses, so that if a pilot hits a virtual object, the course for that pilot gets longer.
While iRacing opened to the public this summer, Sky Challenge is yet to become available to internet participants. A test event is due to be held next week on October 2nd 2008, in which two high-performance aircraft will race head to head through the virtual course over the beaches of Barcelona, joined by a third virtual aircraft controlled from a computer gaming console on the ground.
Climbing the ranks
In both games, participants must work their way up the ranks. In iRacing, drivers are grouped according to skill level so that races are evenly matched.
"New people coming in learn the ropes and as they develop skills they can move up and start to drive faster and faster cars," Mr Kaemmer explains.
Similarly, in Sky Challenge, internet participants start by practising alone, then once they've learnt the course they race against other online players, finally earning the chance to take on the real pilots in a real-time race.
"Our world champion pilots are flying the same course as the internet community - at the same time," said Mr Newport.
Clear enough of these and you'll race the pros
iRacing also offers participants the opportunity to compete against real champions. "We have quite a few professional and amateur race drivers, so its not unusual for people to find themselves in a race with Dale Earnhardt Jr, Justin Wilson, A.J. Almendinger and many more," said Mr Kaemmer.
Games like iRacing and Sky Challenge offer players the opportunity to participate in sports that, because of the expense, they are unlikely to be able to experience in real life.
In the future, their creators hope that the technology will be used to enable sports fans to interact with all kinds of activities that they are currently limited to watching on the television. Following sports looks set to become an altogether more interactive activity.
"I think that this has the potential to be a very interesting new way for fans of a sport to get to know more about the sport and actually get in and participate," said Mr Kaemmer. "It could become sort of an adjunct to television."