The Song of Ice and Fire RPG doesn't just allow you to have adventures in Westeros – it lets you inhabit Westeros, creating your own noble house to vie for control of the Seven Kingdoms and play the Game of Thrones.
I've played dozens of RPGs and read dozens more. Very few have fired my imagination (and stirred my gaming group's excitement) the way the Green Ronin's Song of Ice and Fire RPG has. The SoIaF rules start with a very simple basic mechanic that lets you get on with the business of plotting, betraying, and scheming. It then builds more complex systems on top of that mechanic, systems that dovetail with George R.R. Martin's rich and often brutal world.
The basic mechanic works like this: a given task has a target number based on its difficulty. Each character has a series of Abilities, like Persuasion or Marksmanship, with a simple rating that tells you how many six-sided dice to roll when you make a check with that Ability. You might have a 3 in Marksmanship, so when you fire an arrow at a target, you roll 3 D6s, adding their numbers together to see if you've met or exceeded the target number.
Within each Ability are a number of Specialties that give you bonus dice in certain situations. The Deception Ability, for instance, has Specialties for Bluff, Cheat, Disguise, and others. So if you had a Deception score of 4 with a 2B Specialty in Disguise, you would actually roll six dice when making a Disguise check. However, the bonus dice do not add to the overall total – you take the four highest rolls of your six dice and add those together, discarding the lower two. Bonus dice increase your chances of hitting a high total without making Specialties too powerful.
Character creation uses a point spend system to buy Abilities and Specialties. There are no classes or levels, so you can mix Abilities, Specialities, Benefits (which are a lot like feats in other RPGs) make whatever type of character you want. A noble knight, a deceiving maester, a seductive prince, a nimble mercenary expertly trained in the healing arts – the flexibility is amazing. Characters are not perfectly balanced (Westeros is not an egalitarian place after all) – a random roll determines your character's age, which sets the amount of experience you can spend, but which can also result in various afflictions or frailties.
While you have total control over the character you build, reacting to random rolls on a series of tables makes the creation process tremendously fun. These tables help you build a story for your character that fits into the world of the novels and TV series. The tables indicate elements of personality or history, but only in very broad strokes. The background events table, for instances, has entries like, "You were falsely accused of a wrongdoing," and, "You had a torrid love affair." As you go through the process, you piece together these story and character fragments into a cohesive backstory. One of the characters we created was a naïve, idealistic knight who pines for a Dornish princess. The low status of his house and the fact that he was accused of participating in an attack that blinded her add a tragic element to his story, along with the fact that the smallfolk believe he's cursed.
Instead of your typical adventuring party, the players in the Song of Ice and Fire RPG are all members of the same noble house. The creation of the house is just as interesting and fun as character creation. Because creating a house is a joint activity for the entire group, we've found that it actually makes for a great "story game" on its own. We've created a fallen house that chose the wrong side in the Greyjoy Rebellion and seeks a return to glory by pleading forgiveness from Ned Stark, and a family of reclusive eccentrics claiming lineage to the children of the forest. There are extensive rules for creating your house's colors and coat of arms, and you even get you come up with your own house words.