F# is a free, very simple, tabletop RPG system, inspired by FATE, which in turn is a heavily modified version of FUDGE. The system includes an optional set of "Collaborative Character Creation" rules.

Game Type: 
Roleplaying Game
Collaborative Story
2 - Focus/Imagination

The GM and the players are all working together to create a fun and exciting story. Each game setting has three tag lines. These establish the theme of the game.

Each PC starts with up to three catch phrases, and up to three backgrounds. Tag lines, catch phrases, and backgrounds are collectively called “aspects”. Every aspect has a value, and these initial aspects all start with a value of 1. Mechanically, all aspects are identical; the names “tag line”, “catch phrase”, and “background” are only there to give an idea of how those aspects should be thematically structured. The values of aspects are ONLY important during die rolls.

From the author:
One important note is that F# is designed to be more collaborative than most roleplaying game systems, and to take a lot of the crushing burden of coming up with and keeping track of everything off of the GM. The players of an F# game are involved in the storytelling and creating challenges for each other almost as much as the GM is, although the GM has the general structure of the adventure in mind and keeps things on track. To this end, I recommend that all of the players have some experience with GMing, either in a previous roleplaying game, or by playing this game as a round-robin with the GM changing every session or two.

Have you played it?