Right now I’m working on a game which takes the framework of Dungeons & Dragons 4th Edition and places it into a space opera milieu. One of my reasons for undertaking this project was to find a way to legally do a retroclone of 4th Edition, an edition of D&D not released under the OGL. (A petition exists, if you're interested.) It’s closer to 4th than some similar games like Strike! or Rob Heinsoo and Jonathan Tweet’s own 13th Age, which both go in their own directions, but there are some significant differences. Inevitably trying to pay tribute to an edition which made some radical changes in the name of balance and consistency ends up with you making ever more changes in the name of balance and consistency.
However, in the course of trying to tinker with 4e, I’ve learned a lot about how the system is built, and the underlying assumptions that make it work as well as it does. So while I work on Grand Well-Balanced Space Opera Project , I think the fastest way to actually make all this accessible to the OGL community is to share what I’ve found and talk about how it might be adapted for use in your own OGL stuff. Obviously you can’t just drop the 4e Fighter into a Pathfinder game and expect him to play the same, but you can, with effort, build something that works.