I’ve never played Farmville, so this essay is a good explanation of what it is, how you play it, why you play it, and why it should concern you.
The secret to Farmville’s popularity is neither gameplay nor aesthetics. Farmville is popular because in entangles users in a web of social obligations. When users log into Facebook, they are reminded that their neighbors have sent them gifts, posted bonuses on their walls, and helped with each others’ farms. In turn, they are obligated to return the courtesies. As the French sociologist Marcel Mauss tells us, gifts are never free: they bind the giver and receiver in a loop of reciprocity. It is rude to refuse a gift, and ruder still to not return the kindness.
We play Farmville, then, because we are trying to be good to one another. We play Farmville because we are polite, cultivated people.