GURPS Deadlands is a tabletop roleplaying game set in the Weird West variant of the Deadlands setting. This is an alternate history setting in which a covert war is being waged against demonic entities in the American West in the late 19th Century. It combines elements of the western, steampunk, horror, and fantasy genres.
GURPS Deadlands was created for the Third Edition rules, but can be converted to Fourth Edition without much trouble, with the help of the GURPS Update conversion guide. The magic system can be used as-is, since it is a version of the default GURPS magic system modified to fit the setting. Harrowed or Blessed characters could be confusing to convert, however. Players can get help on the Steve Jackson Games GURPS Forum if needed.