Phonk

West of Loathing and Shadows Over Loathing might fit the bill here. The heavy amounts of surrealist humor are definitely not for everyone though.

I’ve mostly been running the Without Number systems by Sine Nomine (Stars/Worlds/Cities Without Number). They’re rules light ENOUGH that things don’t bog down in combat, but still allow a extreme degree of player freedom in character creation. Coupled with the GM tools, it’s pretty much the only system I need.