Horror, terror and sanity in Dungeon World? How would / do you model it?
My personal preference is to create a sort of wagering system using Wisdom as currency. Like HP, in a way. Your starting Sanity is your Wisdom + a number based on your class.
When you encounter something that threatens to overtake your sanity, risk between 0 and 3 points, and roll plus that number. On a 10+ choose 2, on a 7-9 choose 1.
– you keep the points you risked
– you resist the effects of fear
– you won’t suffer trauma later
Something like that.
The goal here would be to create a move that;
1) shows a slowly dwindling supply of mental fortitude
2) doesn’t ever take away player agency
3) reflects mechanically the narrative of being “afraid” etc