Open Gaming 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.
