As creatures use up stamina, they can become fatigued. This condition stacks with itself up to a maximum of ten stacks, and at ten stacks it turns into ‘exhaustion.’
Any time a creature travels on foot a number of hours equal to their Fortitude, they become Fatigued.
Any time a creature performs an action they don’t have the stamina for, they go to zero stamina and gain 1 stack of fatigue for each action point the action would cost.
Creatures take a -1 penalty to their SPD for each stack of fatigue they possess, and a -1 penalty to their STR and DEX stats for half of their stacks (rounded down). Once a creature becomes exhausted, they keep the full penalties of all stacks of fatigue but also double all Fortitude damage they receive, and cannot gain or use stamina until the ‘exhausted’ condition is lifted. Exhausted creatures are considered ‘Staggered.’
Resting for thirty minutes will reduce Fatigue by one stack, and eating a full meal over the course of an hour will remove an additional three stacks. Exhaustion requires a full eight hour sleep to be removed, and until doing so Fatigue stacks cannot be reduced by more than one an hour. If an exhausted character loses all of their fatigue stacks, they are no longer exhausted.