Quests (and TTRPGS/play-by-post games in general)

[pinkunz]

@Pebblerubble

GURPS: Universal system, good if you want mix of historical/fantasy/SF for example time travel or multiverse.

Fun fact, the original Fallout was supposed to be a GURPS videogame. In fact, the SPECIAL system used by the game is a bit of a bastardization of GURPS.