Fudge is a generic role-playing game system for use in freeform role-playing games. The name "FUDGE" was once an acronym for Freeform Universal Donated (later, Do-it-yourself) Gaming Engine and, though the acronym has since been dropped, that phrase remains a good summation of the game's design goals. Fudge has been nominated for an Origins Award for Best Role-Playing Game System for the Deryni Adventure Game.

Rather than being a rigidly pre-defined set of rules like d20 System or GURPS, Fudge offers a customizable toolkit for building the users' own specialized role-playing game system. Such things as what attributes and skills will define characters are left to be determined by the Game Master and players, and several different optional systems for resolving actions and conflicts are offered. Fudge is not tied to any particular genre or setting and world builders are encouraged to invent appropriate attributes and rules tailored to the campaign.