RFactor

rFactor is a PC racing simulation video game developed by Image Space Incorporated (ISI) and released in 2005. It is designed to deliver realistic driving physics, tire modeling, and vehicle behavior, with a strong emphasis on accessibility to a wide range of user-generated content. The game runs on Windows and includes online multiplayer support, as well as a modular platform that enables modders to create new cars, tracks, and racing series.

Central to rFactor's appeal is its open architecture and active modding community. Players could download and install community-made content via the rFactor Central hub, which hosted cars, tracks, and leagues. This contributed to a large, ongoing ecosystem of mods and long-running online competitions, helping to popularize community-driven content in racing sims.

RFactor influenced the development of later racing simulations and laid groundwork for professional-grade sim racing workflows. Its sequel, rFactor 2, released starting in 2012, was developed by ISI and later taken over by Studio 397. rFactor 2 introduced updated graphics, revised physics, and an updated online platform while retaining robust modding support and a focus on realism. The original title remains part of the history of sim racing and is noted for fostering a durable modding culture and competitive online communities.