Ranked in these QuestionsQuestion Ranking
Pro No special dice required
The game can be played with common six-sided dice.
Pro There are theme-related books available to start various types of games
D6 Space is West End Games old "Star Wars D6" game with all of the licensed Star Wars names removed. It's a stand alone complete game.
D6 Fantasy is a standalone ruleset for running a D&D type game with the D6 system.
D6 Adventure is a standalone ruleset for using the D6 system in a Wild West, spies, or modern adventure game.
All three have supplement books (Spaceship design, magic, aliens, etc).
Pro A simplified variant, called Mini Six, is available
Mini Six is a fan-made variant of Open d6 that aims to be a distilled version of the Open d6 system.
Pro Includes rulebooks covering the more common genres
Open d6 includes rulebooks for Fantasy, Adventure and Space settings.