The USP in The Witch at the Abyss is, of course, the alchemy system, where you brew potions. Here, I want to develop a logical game out of ingredients that behave like variables, bools, logic gates, and even higher algebra. An example: Ingredient: "Rewurzling" with the ability: Reverses the last effect of any potion. Potion A: Heat, Protection; Potion B: Protection, Heat; Both potions would initially do the same thing, giving the consumer protection from heat, regardless of the order of the ingredients used.

In Potion A, Rewurzling would turn the potion into: Fire, Weakness.

In Potion B, on the other hand, it would become: Protection, Cold;

because Rewurzling affects the last effect, which is no longer Protection but Heat. Suddenly, the order of the previous ingredients matters, since we are now doing more with the potions. Maybe there should be a limit for the number of ingredients per potion, but I like the idea of individual brews with unbelievable consequences of alchemy.