bribe players for participating in its viral spread: cute lonely animals will show up on your farm periodically and as a player you face a dilemma in sentencing them to virtual abandonment and death unless you post on your Facebook wall that you need one of your friends to start playing Farmville and "adopt" the adorable little self-promoter

Farmville bestows ample amounts of beginner's luck on anyone who's just starting, but gradually puts the brakes on their pace of progress until going from level 23 to 27 will mean doubling all the experience you've earned up to that point.

Farmville is designed to draw you back in small doses scattered throughout the day. In Harvest Moon you plant crops and keep yourself busy while in-game days pass, in Farmville you plant crops and harvest them on a real-world schedule

In order to quit Farmville you'd have to make a conscious choice after harvesting your fields to not re-plant them, or else leave all your currently planted crops to die. Some of my friends have even handed out their Facebook passwords to get their friends to babysit their farms for them when they're on vacation

Farmville does seem consciously designed around that goal: it virally spreads itself throughout your social network as innocently as it can, and subtly convinces players that it's more worthwhile to pay actual money than spend all their time farming to get ahead, and tempts them with decorations you can't achieve any other way.