CthulhuFnord
Mongoose
I've been thinking about how to introduce Cthonic and Cthuloid Horrors into Runequest and other MRQ settings. I'd rather not introduce the Sanity mechanics from CoC, I like them but it adds another layer of complexity to the MRQ system. Instead I'm considering giving powerfull Mythos critters a Fear rating based on the Divine Spell Fear. More powerfull or Horrible creatures would have a corespondingly higher magnitude. The Fear effect would always be on and can not be dispelled, although it would only effect you once per encounter.