GURPS Fourth Edition is a 21-book series with 21 released primary works first released in 2002 with contributions by William H. Stoddard, Peter Dell'Orto, Dan Howard, Matt Riggsby, Steve Jackson, David L. Pulver, Sean Punch, S. John Ross, Daniel U. Thibault, Michael Suileabhain-Wilson, Phil Masters, Jonathan Woodward, Kenneth Hite, John M. Ford, Jon F. Zeigler, James L. Cambias, David Morgan-Mar, Shawn Fisher, Michael Hurst, Hans-Christian Vortisch, Kenneth Peters, Jake Steinmann, and Jason "PK" Levine.