Fudge has long been my favorite RPG system, mainly because it is one that encourages tinkering with the system to match the style of game that best suites you. That being said I figured this place would be as good as any to explain the rules of Fudge as I run it so that if I ever have enough time to actually run a game again I'll be able to point here and not to a 200+ page pdf.
At it's core Fudge runs on what's called the Trait ladder, going from Terrible(-2) Poor(-1) Fair(0) Decent(+1) Good(+2) Great(+3) and Superb(+4). In almost all instances you roll 4df add the result (which will be between -4 and +4) to a trait.
Rolls are modified when necessary by err, fudging, the results of a single die, for a ¼th (or minor) bonus - → □. A ½th (moderate) □ → +. A ¾th (major) - → +. This can loop around with a bonus of 1+ a minor, and so on. If a dice roll doesn't produce a die you can fudge, use the next lower bonus.
Roll penalties are handled the same way, just reverse the direction you flip the die.
Fudge characters are defined by 4 main aspects: Skills, Attributes, Gifts, and Flaws.
Fudge is a skill based system, that is what your character can do is biased on what skills the character has, every skill is ranked on the trait ladder. By default if a character isn't trained in a skill, they will have an effective level of Terrible(-2) in it, although more complicated skills could be worse.
Attributes, such as Strength can act as both generic skills, and also as HP. By default all attributes are Fair(0). When treating Attributes as HP, every 2 wounds received reduces the Attribute by one level Decent(+1) to Fair(0) and so on, if a attribute is reduced to sub-Terrible, that character is incapacitated. If a character then takes 6 more wounds to that attribute the character is dead.
Gifts are ways that your character stands out from the crowd, this can be things like social status, or supernatural effects, or even just simple being exceptionally well trained. Every gift has between 1 and 4 boxes associated with it, this is the number of times you can use that gift actively. For example you might always be a member of High Society, but you can only call in so many favors.
Flaws are things that limit your character's actions, like code of conduct, or enemies, or supernatural weaknesses. Every time a flaw takes effect you can recharge two uses of a gift, in essence, playing up your flaws powers your gifts.
Moving onto Combat, during that situation there are typically 3 things a character can do, Move, take action (attack) or create an advantage. During a character's turn they can do any 2 of these 3 things. They can do the same thing twice.
The basic types of trait checks are Unopposed, in which you roll, hoping to beat a static result, like needing a Good or better result. And Opposed where you and an opponent both roll, with the spoils going to the victor.
Some rolls are also defined by the Rolled Degree, how well (or poorly you rolled) if you got a Good(+2) result against a Poor(-1) target the Rolled Degree would be +3.