Add a new rule called “Happiness”:

Each Bill Murray has a number of Happiness, which is tracked in the GNDT, and shall initially be 50. The maximum Happiness is 100; the minimum is 0. Once per day, any Bill Murray may decrease each Bill Murray’s Happiness by the Atmospheric Depression, if such a number exists; but only one Bill Murray may perform this action per day.

Add a subrule to the rule “Happiness”, called “Groundings”:

A non-grounded Bill Murray gains Happiness equal to the amount of steps taken to perform a Good Deed, after they perform said Good Deed.

Set each Bill Murray’s Happiness to 50.