Open Gaming License
Kobold Press begins playtesting Tales of the Valiant, a D&D 5E spinoff
Back in January when Wizards of the Coast backed off of Open Gaming License (OGL) updates to go with their new edition of Dungeons & Dragons, they also made a second decision that -- while popular -- hadn't seen as much fanfare as of yet: they released the current D&D rules as a System Reference Document, or SRD under a Creative Commons license.
Retroclone RPGs are a unique way to play the old tabletop games you can’t get your hands on anymore
If you've never heard of a Retroclone RPG, it's not surprising -- they're a result of the fact that RPGs as a hobby are starting to show their age.
Off Topic: What is a System Reference Document and how can it make your life easy in D&D?
In my post about Pathfinder I talked a lot about the Open Gaming License which allowed Paizo to take the revised 3rd Edition of Dungeons and Dragons and essentially create Pathfinder out of it.