Thinking about watching the series and making a quick Labyrinth Lord / Swords and Wizardry / whatever other retroclone writeup about the world and the people and places.
It's a pretty evocative work of fiction, and I think that it could make for a pretty compelling gameworld. It's got a lot of similarities to the Cantina scene in Star Wars, except extrapolated to the whole planet and run by a shapeshifting master of evil. What's not to like about that?
Of course, it'd be a lot of "work" (can you really call watching the entire run of Samurai Jack work?), and would take a lot of effort, but it'd probably be worth it.