Fudge is game developed in the early 90s on the internet by Steffan O'Sullivan. Specifically the rec.games.design on the old Usenet forum. The Wikipedia article has live links to the original post so you can read them yourselves.
It is a toolkit meant to be refined for a specific game. The core rules have a wealth of options that a referee can choose from to make the game he wants. Anything from extremely lite and freeform to very crunchy.
Fudge in a Nutshell sums up in two pages the heart of the Fudge mechanics.
Fudge characters are defined by attributes, skills, gifts, and faults. When there is a rating like for a Strength attribute or Piloting skill it uses the fudge scale; from low to high; Terrible, Poor, Mediocre, Fair, Good, Great, Superb. If you don't like the descriptive scale you can use numbers with Fair = 0, Mediocre = -1 and Good = +1 and so on.
Fudge assumes that one attribute level = 3 skill levels, 1 gift = 6 skill levels, 1 gift = 2 attribute levels, 1 gift = 1 fault.
Coupled with this is the concept of scale. In a human focused campaign a human being has a scale of +0. It is primarily a rating of Strength and Mass which is mostly applied to the ability to deal damage and to withstand damage. Each +1 scale give the character 1.5 times the mass of a ordinary human. The rules have examples of scale equated to various real world and mythological creatures.
The elegance of this system is that the resolution of two creatures at the same arbitrary scale works the same as resolution of two humans. So if two pixies at scale -7 go at it the system work just as well as normal human combat. The same with two dragons. For fights between two creatures of different scale in general the larger creatures will do more damage and have the ability to withstand more damage than the small creature.
Action are resolved by either an opposed roll or a roll against a target difficulty. In an opposed roll the two sides will have a skill or attribute level. For example a fighter with a sword skill of Good and a mage with a mediocre dexterity. Both side roll 4dF generating a number from -4 to +4. For example the fighter rolls a -1 and the Mage rolls a +2. Like GURPS 3d6 roll the result is a bell curve. The result is applied to the two sides skill and compared. For example because the Fighter rolled a -1 he only gets a Fair result as Fair is one level lower than his Good sword skill. The mage in contrast has a Good result as his +2 roll is applied to his mediocre dexterity raising it to Fair and then Good. In this roll the Mage successfully dodged the fighter's sword swing.
For unopposed rolls the skill or attribute is compared to a target difficulty set by the referee. For example the Fighter has a good strength and is trying to lift the portcullis gate up. The referee rules that he need a Great result. The Figher rolls 4dF and gets a +1. This is applied to his Good strength raising it up by one level to Great. The gate is wrenched up.
The Fudge core rules gives several ways of resolving a successful combat hit. Fudge spends the most time on a wound level system. Characters can be undamaged, scratched, hurt, very hurt, incapacitated, or dead. Typically you can take 3 scratches, 1 hurt, and 1 very hurt. If you already taken all the damage you can at a particular level it is applied to the next worse level.
Again this is summarize nicely in Fudge in a Nutshell. Also the core documents are released under the open game license which means you are free to adapt and publish them for your own use.
So why Fudge? As readers of this blog know I am a long time fan of GURPS. While developed independently Steffan and those helped have strong connections to GURPS and many have written GURPS books. So while Fudge is not GURPS it shares some DNA like the bell curves and allows for attributes to be the primary component of a skill level as well as advantages i.e. gifts and disadvantages i.e. faults.
And what it comes to is that I want to publish my GURPS material along with my Dungeon and Dragon material. Since GURPS doesn't have an open license, to me Fudge is the next best thing. And the fact that Fate, a closely related game, is popular system for many doesn't hurt either.
My focus is implementing Fudge for the type of fantasy games I been running for the past 30 years. Building on the things I like about the various games I played over the years. There is a lot of inspiration from GURPS but also I am inspired by Hero System, Fate, Runequest, and other games I have played over the years. The result is I hope a fantasy game that is allows for skill based character with a moderately detailed combat system using the fantasy tropes of the world's most popular roleplaying games that is easy to get into and that because of it common heritage with Fudge and Fate easy to add new elements of the referee's choosing.
And thanks to the development of the internet and the progress of technology, when I am done writing this it is easy to share it in an attractive format with the rest of you. Like Blackmarsh and my other open projects the PDF will be free I will charging for the physical book.
I am shooting to get this done by the fall of 2014, I have some other projects to complete first that are priority like a certain English Civil War setting. In the meantime I will play one off games and then when the rules are settled enough I will start a playtest campaign. And of course I will be sharing the development when I have something usable.