GURPS Infinite Worlds is a supplement for the Fourth Edition of the GURPS role-playing game, published by Steve Jackson Games in 2005 and written by Kenneth Hite, Steve Jackson, and John M. Ford. It expands upon the campaign setting of conflict between the Infinity Patrol, which is the dimension-jumping agency on "our" Earth, referred to as Homeline, and Centrum across a multiplicity of alternate history Earths. This was presented in the Fourth Edition GURPS Basic Set (and originated in the Third Edition supplements GURPS Time Travel, GURPS Alternate Earths, and GURPS Alternate Earths II). Contents GURPS Infinite Worlds builds on the idea of player characters travelling from one world to another, even across genres, for the fourth edition of GURPS. GURPS Infinite Worlds has eight chapters: Infinity Unlimited, Enemies Everywhen, Present at the Creation, Worlds Enough, ...And Time, Infinite characters, Infinite Campaigns, and Alternate Infinities. Infinity Unlimited This chapter describes one of the two worlds (known locally as Homeline) that have full-fledged, public "parachronics" programs (the technology behind traveling between parallel universes). Travel between worlds is generally done through ground-based equipment ("projectors") or vehicles ("conveyors"), but magic, parahuman abilities and even stranger methods can and have been utilized by both. Alternate worlds (also known as realities or worldlines) are grouped into "quanta", which have varying degrees of ease of access not only to Homeline but to her opponents. Enemies Everywhen This is the chapter that describes Homeline's adversaries and hazards. The major adversary is Centrum, the only other reality known to have a public parachronics program, who can be played as a deadly adversary, occasional opponents or grudging allies depending on the GM's preference. The secondary adversary is Reich-5, the worst of the five known 'Nazis win/survive WWII' realities in the setting. An ill-advised raid by Spetsnaz troops from Homeline Russia resulted in the capture of a troop conveyor, a handful of live prisoners, and the corpse of a scout with a genetically-linked psionic world-jumping ability. A quick-thinking local Brigadeführer made a deal with the mystical SS society of the Ahnenerbe to take possession of the booty (and to keep it all secret from the mainstream Nazi hierarchy); Reich-5 scientists and sorcerers are using occult rituals and horrific medical experiments to slowly spread their Thousand Year Reich to other realities. Present at the Creation This chapter describes how to create your own alternate reality and offering inspirational concepts to look