Not very formal, sort of stream of consciousness, but here are some thoughts:

Honestly, the whole thing struck me as a social game that had the pleasant mindlessness of a coloring book, combined with a little optional math and Sims home decorating -- on a Neopet/Tomagachi framework (feed it or it dies, take care of it and it smiles). Plus the usual progressive reward system and social game bits.

But it's actually a pleasant rhythmic thing to have an excuse to tap your friends and tell them you care (whether you actually do or not..). ... See More

There's something irrepressibly nice about logging in and seeing that a friend tended your crops and fed your chickens while you were gone. When you find something special, you can share it with your friends -- and of course, you get bounty they share with you.

There are time-limited seasonal minigames, like the current leprechaun gold people are collecting and sharing for St. Patrick's Day.

And there's a collector magnet, in terms of limited time availability titles and virtual goods.

All in all, it's a happy game, kind of like playing a simple card game over a mellow evening with friends, but asynch and not much actual talk.

For the achievers there's a point system, for the artists there's a competition for the prettiest/most creatively laid out farm of the week.

And for so many internet users, shut in our little urban boxes, there's a nostalgia for brushing a calf or planting and harvesting a field. This is a sanitary outlet for that nostalgia, no manure, no real labor. A social passtime where you can't really *lose* (although if you let your crops whither, you either have to pay real money to revive them or rebuild your reserves).

The Zynga business model is another thing -- and that's a lot of what I was studying too (without participating -- I didn't actually spend a dime). There are special things you can get only with the bought currency. I can see how it's a micropay cash-mill for them.

A *lot* of people play. I have people in my social circle who I'm actually pretty stunned by how much time they've put into this game, obviously visiting it for significant time (1/2h-1h) several times a day. Critical mass is pretty important to this kind of game. If you don't have active friends, there are things you can't do (like expand your farm) without paying cash -- so there's an incentive to assimilate your friends into the borg.

Plus, there are offers you can take from marketing folks mostly (many of which have the reputation for being kind of gray and scammy -- I think TechCrunch called them on that a while back) that give you the bought currency without you spending money -- at Zynga -- but most of those offers require spending money eventually with the promotional partner.

There's nothing worse about Farmville than there is about being hooked on, say, a daily soap opera, assuming you aren't going broke or neglecting things over it.

On the other hand, it makes me reflect on my own habit of engaging in the fantasy of killing monsters, beasts, and people -- to relax. Virtual farming just can't hold my interest. But what does that say about me? :)

Really, what I think it comes down to, is that my sense of achievement through mastery of a system, through strategy, and my puzzle solving circuits are just not engaged by these games. My reasons for gaming are different.

For the record, I'm currently playing mostly Eve Online, which is probably the uber geekiest game, an arbitrarily deep sandbox of user created economics/politics (and blowing shit up). About as far from Farmville as you can get and still me a massive multiplayer online game! :)

And, of course, I'm developing a psychotropic social dancing virtual world based game. So call me Homo Ludens...:)