From Chainmail to D&D Next
I have not played this version of the OGL yet. But I think it is influential in the way it recreates character creation. There are now three parts to a character: Race, Class, and Specialty. The focus on skills has had been increased, and feats are better organized. Gear has become important again. Another nice thing is the streamlining of combat, by removing multiple attacks for fighters and attacks of opportunity.