Freeform Universal Do-it-yourself Gaming Engine (FUDGE or Fudge) RPG is a flexible RPG rule set. Fudge is available as the Fudge 10th Anniversary Edition, a deluxe hardbound book with bonus materials or as the older Fudge 1995 Edition, a free PDF. Fudge was created with game designers in mind. All the rules are optional and there are numerous ways of doing things, especially in the Fudge 10th Anniversary Edition. For instance Fudge provides numerous options for combat, describing the pros and cons of each option. You can choose to have detailed damage options, critical hits and such, or you can read the tips on going diceless and using narration-based combat. You can play Fudge as a minimalist RPG system, ignoring most rules for the sake of simplicity or cinematic effects, or use more rules to create a simulation-like RPG.
Another major innovation is the Fudge dice (as mentioned in our review of Spirit of the Century, an RPG derived from Fudge). Fudge dice are designed to produce statistically average rolls, tightly controlling the rampant randomness found in many paper RPGs.
Fudge Dice: four six-sided dice are used with these six facings, [+], [+], [ ], [ ], [-], [-]. Plus represents a +1, and minus represents a -1 and blank represents a 0. In effect, Fudge Dice are three-sided dice. Fudge Dice were created by the Fudge RPG designer, Steffan O'Sullivan, who wanted more average, bell curve-like results from dice rolls. FATE RPG is derived from the Fudge RPG, hence Spirit of the Century also uses Fudge Dice. Using Fudge Dice ensures that average rolls are made and that randomness still exists but is better controlled.
Versus Rolls: when a difficult task needs to be accomplished, a versus roll is made. Four Fudge Dice are rolled and added to your skill level, then compared to your opponent's skill or task difficulty; the higher result wins. For instance my character used his scientific skills to identify the tripod landwalkers -— my Superb (5) science skill versus Great (4) difficulty. I rolled [+], [+], [ ], and [ ]; that sums to +2. the GM rolled [ ], [ ], [-], [-]; that sums to -2. Thus my character's Superb (5) science skill was upped +2 to Fantastic (7), while the task difficulty was downgraded -2 to Average (1), and thus I was able to determine that the walkers were of Martian technology, and where on Mars they were from.
If you want to make your own computer RPG or are looking for a flexible paper RPG, reading Fudge will save you time and headache.