With Frogboy posting the Stardock roadmap (https://forums.elementalgame.com/404765), it reminded of that long forgotten project Society.  For those of you that don't know, Society is a prototype RTS MMO game, where players fight and trade over provinces and resources to try to become the big boy on campus.
Now that the Elemental game franchise is in full swing, I feel it is time we discuss what a free to play game like Society needs to be successful.  While there are quite a few games using this model today, the ones I will use to compare are Hattrick.org, a soccer management game, and league of legends, an RPG/RTS hybrid.  Here are my thoughts:

1.  Community

Free to Play games need more than just viral marketing- they need to make a committed player base.  This boils down to one thing: involvement and engrossment, or the bait and the hook.  Games use various aspects to "bait" users and get them involved - that is, playing the game on a regular basis.  Farmville has players logging in daily to harvest and replant crops.  Hattrick has players checking in twice a week to arrange practice matches and set their formations for the upcoming match.  League of Legends has "first win of the day" bonuses, which give users an incentive to playing one match a day.
The second part is the hook.  Anyone can make a button that benefits a user to press daily, but you need to make that benefit worth fighting for.  Hattrick does this by making users attached to their league and National Team.  While actually helping your nation's soccer team is pretty easy and uninteresting, working and communicating with other users to do so really drives users to success.

Both Hattrick and League of Legends have direct competition, which leads to direct satisfaction for winning and frustration for losing.  Both encourage users to invest more into the game and try harder next time.  More than this, though, direct competition has players working with and against each other, and this involvement keeps users interested and invested in the community of the game.

2.  Player Satisfaction - Accomplishments  

While Community is a huge aspect of what makes a successful F2P game, rewarding users for their time and energy is what initially hooks them to the game.  Without a game focused on hitting the next level or getting the next star, users will feel stagnant and tire of the game.  For competitive games, this means giving users a series of benchmarks that they can judge themselves and their improvement by.  While competitively and tactically speaking, Hattrick is a pretty dull game, it has loads of ways to compare yourself to your previous self.  This includes how you rank in your league one soccer season to the next, how big your fan club is, how good your best player is, and how much money you have in your bank account.  In League of Legends, players can see their player level, ELO ranking, and unlocking new content.
3.  Revenue

Everything can be broken completely by the wrong income model.  There are F2P games like Hattrick and LoL, and there are what I like to call "Pretend Free To Play" games, which pretend to be free but require a player to put in money to be competitive.  There is a careful line that must be drawn as to what a player needs to be competitive and what a player wants to increase their entertainment value.
Hattrick gives players the ability to pay a small monthly fee, and in return they get additional features that do not effect their competitive level - at least not directly.  These include additional statistics and cosmetic features.  League has a different model, using micro-transactions to let players purchase cosmetic upgrades, as well as purchase boosts which decrease the time it takes to unlock new features.  While these boosts would make a persistant sports team unbalanced, the finite match time makes this model viable for League of Legends.

So, now that we have some elements for success defined for the Free to Play model, where can Society fit in?

1.  Community

Bait - Encouraging players to log in to do basic maintenance on their society will be positive.  This should not feel repetitive and dull, but instead involve an interesting choice - perhaps about what they want to focus on improving that day.  In the beginning this is pretty easy, with building new farmlands and marketplaces, but later on this should mean deciding whether to drill your militia or research a new technology.
Hook - What are users fighting for?  They want to make a name for themselves.  They want to increase their population.  They want to beat out their trading competitors on their continent.  These need to be small scale enough that every user can see and improve something on a month to month basis, but with a big enough system for it to repeat indefinitely.  Users need to move from their first small pond of little fish to another pond with bigger fish, but without increasing the size of the pond (and making the user feel like they've leveled out).    The other part of the hook is involvement with other users.  They need to be able to work with others, but without simply teaming up and picking on smaller users.  This means investing in worldly expeditions, and implimenting some sort of meta-game competition.

2.  Accomplishments

This is where Society can really shine.  You have all of the basic aspects of civilizations to measure yourself by - army size, population count, territory, culture, and money.  All of these factors should give players something to shoot for, even if they are the smallest fish in the smallest pond.  There are lots of cool ways to reward players, like cool titles and new buildings.

3.  Revenue

Society needs to feel like you can play the game from start to finish without investing a dime, but at the same time make users feel like they really want that new shiny item.  So while giving a player a machine gun upgrade would be bad, letting them pay extra to see black knights fight against their opponents generic calvary would be a good idea.  With Elemental's buildings, it is easy to see where making new cosmetic content is cheap and easy.  And if you let players design their own stuff, adding an extra doodad to place on their tile is still worth selling.

In addition to this per-item cosmetic option, you also have the ability to create a subscriber section.  This is where users can pay a reasonable monthly fee to have a cleaner user interface, world rankings, statistics, what their royal family looks like, etc.  Because of Society's persistant nature, it would not lend itself to selling boosts to experience and rewards, but there is a lot of room for informatitive features that people would shell out for.

So there you have it - thats my run-down of how I see Society fitting into a Free to Play model.  What do you think?