GURPS Infinite Worlds

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.