rFactor is a computer racing simulator designed with the ability to run any type of four-wheeled vehicle from street cars to open wheel cars of any era. rFactor aimed to be the most accurate race simulator of its time. Released in November 2005, rFactor did not have much competition in this market; however it featured many technical advances in tire modeling, complex aerodynamics and a 15 degrees of freedom physics engine.
rFactor was developed by Image Space Incorporated (ISI), which has been developing race simulators since the early 1990s for both commercial and military purposes. The gMotor-engine2 on which the game is based is a direct successor to the engine used in previous titles developed by ISI, most notably F1 Challenge '99-'02, released through EA Sports. The gMotor2-Engine was also used in many Simbin-games, including GT Legends, the GTR-Series and the Race-Series. A modified version of this engine was utilized by The Sim Factory for ARCA Sim Racing. A special version of rFactor was available for business application, for example for event simulators or promotion.
rFactor has a detailed interface during offline race sessions or online games, allowing players to control the mechanical setup of their cars, chat to other players, and enter the racing arena in their vehicle. The player's car can be driven from multiple viewpoints, but the two most popular are termed the cockpit view (from the driver's eye) and swingman view (above and behind the vehicle).
The vehicle is best controlled using a computer steering wheel, although a joystick or even keyboard can be used. The keyboard is also used for some actions, like requesting pit service and adjusting brake bias. This is analogous to buttons on modern racing car steering wheels, and most computer wheels have buttons that can be mapped to keystrokes. The player can jump directly from the racetrack to the control interface by pressing the escape key (ESC), or entering their pit box.
rFactor has two classes of vehicles, "Open Wheel Challenge" and sedan cars. Open Wheel Challenge vehicles are open wheelers, including 50 HP training vehicles, F3-like cars and F1-like cars (called FormulaIS). The sedan cars range from compact but sporty to BMW-like vehicles and US Muscle cars; they also include stock cars (USAR-like).
ISI announced (in 10 May 2006) a deal with Intel to add the BMW Sauber Formula One car to the game. The vehicle was demonstrated at the 2006 European Grand Prix. The deal was to be specifically to promote the upcoming Intel Core 2 processor. . The BMW Sauber was added in 2006. The respective cars of 2007 and 2008 were released as official add-on.
Developer ISI did not seek to license any series at all, so included only fictitious circuits and vehicles. rFactor was released with just five facilities, comprising approximately 10 layouts, including some which were simply reverse races. The facilities were Orchard Lake (an oval and road course), Mills Park and Toban Raceway (road courses), Joesville Runabout (a short oval) and Sardian Heights (a street race in a city environment). In later updates an extra layout for Sardian Heights have been added, Essington Park, Lienz (a mountain road and rally course) and Jacksonville (a high banked super speedway) were added. Several real world tracks, but with fictitious names, were added to the game as part of an update released in 2006, such as Barcelona (Circuit de Catalunya, Spain), and Nuerburg (Nürburgring).
In addition to the stock vehicles and circuits available in rFactor, a steady stream of unofficial mods has become available. One of the earliest mods was F3 vehicle mod, which became very popular for some time and was later officially included in the game, although with fictitious branding. Many more modifications were released, including ones that recreated seasons from Formula One, NASCAR, IndyCar and V8 Supercars. With the release of the SDK many new venues were created and released as unofficial addons to the game. Many of the circuits for rFactor were converted from other games, including GTR, GT Legends, TOCA Race Driver, Gran Prix 4 and GP Legends.
rFactor is a significant evolution of F1 Challenge '99-'02, but without the licensing of Formula One circuits and teams. As such rFactor's initial release only included four fictitious circuits (seven as of v1.087), with about a dozen layouts within these facilities; there are about six vehicle classes, including two open wheel and four sedan classes. Among its most notable features was rFactor's rich interface for creating custom game contents, which made it possible for amateurs to create additional vehicles and tracks for the game. On August 1, 2006, ISI released the full update,http://www.rfactor.net/?page=news_07-20_updatefeatures 1.150 with many changes and new features, including the new 2006 BMW Sauber F1 and a much requested manual. Another notable and often requested feature was the driver-swapping, which allowed to change drivers during the race, enabling 24hour events like Le Mans.
Despite the highly-developed Artificial Intelligence model, it was subject to much change and criticism. The AI blocking code (which instructs the AI to block other vehicles, preventing passing) was rewritten in response to criticism. Mike Z of ISI has promised that, "AI blocking will be back in a much more robust and logical form for a future update. I concentrated on fixing bugs for this update; in the future I'll expand the range of AI behavior. (probably still fix some bugs too...)". A feature was added to allow the AI to "learn a track", which teaches the AI the ideal way to drive a particular circuit. As of v1.150, the AI was improved, leading to notably faster driving styles. There are minor issues remaining. The AI drivers do not accurately reflect human behavior on a race track, nor realistic human cornering skills. They also suffer from an odd-bump anomaly, whereby they do not take jumps as they should. AI blocking has not returned yet, but computer controlled drivers no longer hesitate when overtaking other cars, whether they be computer or human controlled. rFactor provides an advanced tire model, aiming to be much better than the Pacejka model previously used in most simulators. rFactor's tire model simulates a non-linear tire use cycle according to temperature and wear.
F1 Challenge proved to be popular for online racing over the Internet through GameSpy, which allowed any player to find available games. rFactor has extended this in several ways. The central server is handled by ISI themselves, so finding other games is effectively the same. The central server, however, will show all races and practice sessions over a web interface known as Racecast.http://racecast.rfactor.net There are also career statistics available for registered drivers. Technically, the game server can be run from a dedicated program, free from the need to render graphics, and this machine only needs lowly Pentium 3-class (500 MHz) performance. It can run mixtures of human and computer controlled (AI) vehicles.
In an evolution from F1 Challenge, the circuits now include all layouts at a particular facility, which greatly reduces the need to duplicate track geometry. The game can easily accommodate different sorts of vehicles, and games between multiple classes of vehicles are possible. rFactor also had a plugin-interface for third-party addons to hook in. This allowed for features like screen-overlays or radio chatter.
In the first review of rFactor, published on AutoSimSport, Jon Denton stated: What the tire model in rFactor does very well is that it models the relationship between slip angle, self aligning torque and cornering force - and it does this better than anything that has come before.http://www.autosimsport.net
In March 2009 ISI announced the development of a sequel to rFactor, which will include weather effects, reflections, and accurate shadows on a variety of textures.