Fudge is an easily customizable roleplaying game based around a simple seven-level trait ladder and dice mechanic. Notable aspects of the game are named trait levels (Terrible, Poor, Mediocre, Fair, Good, Great, Superb), custom dice ("Fudge dice" are six-sided dice labeled "+", "+", "0", "0", "-", "-"), and no fixed list of attributes.

The system was developed in 1992 by Steffan O'Sullivan, in the newsgroup rec.games.design. Originally named SLUG (Simple, Laid-back Universal Game), it was soon renamed FUDGE, an acronym which stood for "Freeform, Universal, Donated Gaming Engine". FUDGE was first distributed as a text document under a free license, the Fudge Legal Notice. A limited print edition was published by Wild Mule Games in 1994, which was followed by Grey Ghost Games' 1995 edition. The 1995 edition was the last version with significant changes by the original author, and also changed the definition of the acronym to "Freeform Universal Do-It-Yourself Gaming Engine". The 2000 Expanded Edition, with material from additional authors, dropped the acronym and FUDGE became simply Fudge. The 10th Anniversary Edition in 2005 added even more material, and the same year also saw a version released under Open Game License as the Fudge System Reference Document.