The Forgotten Edition

 Once upon a time there was an edition of Dungeons and Dragons released as pdf only.  This was DRAGONFIST.  

Released in 1999 it got eclipsed and generally forgotten with the release of 3rd edition D&D in 2000. The RPG GEEK entry on it is brief:

Dragonfist, "The Roleplaying Game of Martial Arts Action," was a roleplaying game released by Wizards Of The Coast as a series of free PDFs on their website in 1999. The rules were a heavily modified version of the 2nd edition Advanced Dungeons & Dragons rules.

In November 2002, the rights to the game were sold to Green Ronin, who had planned to release a new version in 2003. However, it seems that the new version was never released and remains in development limbo.

It was a kung-fu action D&D with a fairly innovative range of rules changes and additions. There were the standard 6 ability scores, but they didn't have a fixed bonus. Every class had level based maneuvers with a progression not unlike spell progression. There were kits to detail the 4 character classes of Fighter, Wizard, Shaman, and Thief. There were feats but they didn't work like they would in 3e. Everybody was kung-fu fighting and there wasn't a Samurai or Ninja in sight.