The concept of Social Contract is brought up on the OCT WD and I wanted to expand a bit on it.
The actual definition of Social Contract comes from an Indie RPG forum and is a bit convoluted, but what folks generally refer to as SOCIAL CONTRACT has to do with the expectations of players in a game.
When people get together to play a game; any game, whether Scrabble or 40k or D&D, they all have expectations.
Some people want challenge, some want catharsis. Some are interested in being social and rolling dice with friends while others want competition. Every single one of these is acceptable AS LONG AS THE OTHER PLAYERS ARE THERE FOR THE SAME THING.
This is the heart of social contract.
Before playing games with people, it's important to be up-front about what you're interested in. Be honest about what you expect out of a game. What kind of game do you want to play?
In terms of 40k, it means defining and talking about, up-front whether you are there for competition or just for an occasional bit of die rolling. being honest about whether you are interested in competing or fine-tuning your army list for competition...or just having a quick fun game.
There is nothing wrong with playing to win. There's nothing wrong with playing competitively...or with playing just for fun with no concern for winning or competition.
The trick here is A. Communication. B. Honesty. and C. Playing with people who are interested in the same thing.
Especially with the upcoming Apocalypse but also important in every game, Social Contract is an important tool in ensuring everyone has a good time playing the game.
In Apocalypse the key to the game, the very goal is to have fun and use all your minis to have these massive brawls.
The important thing about Apocalypse is in keeping with the spirit of the game, enjoying the crazy moment and having a lot of fun rolling a lot of dice.
In every game though, as long as everyone playing, you and your opponants are roughly on the same sheet of music as far as what you are playing for, and what you want out of it...it'll likely be a fun game.
When people play for different reasons, the game usually sucks. This is universal. Whether Scrabble, 40k or D&D, if the other players are playing for some other reason than you...I can almost guarantee the experience will be less than somebody hoped for.
Take Scrabble for example:
If I play competitively, taking extra time to score only on the high multipliers against my wife who is just playing for fun, plunking down words as she gets them, she's going to get schooled, and likely not going to have fun because I'm only playing to beat her, interested in my fun not hers.
Alternatively, if I play competitively with another competitive player, we'll likely have fun.
Take D&D for example:
If I'm playing for the role playing experience of it, while others for the tactical warfare aspect, they are going to bored while I RP with the Bard, and I'llbe frustrated with the combat maneuvers.
Alternatively, if I play D&D with other folks interested in heavy RP, or if the combat heavy people play with other combat heavy folks, everyone will have fun.
Take 40k for example:
If I play competitively, and break out my GT list against Tauman and his brand new Tau army, I doubt he's going to have much fun.
Alternatively, if I play Tauman with a quickie fun list and go easy on him, playing just for fun, he'll likely have fun too.
Or Tauman can play another newbie, or I can play another competitive GT player.
The important thing here is talking about it and being honest about your interests in the game, and playing with folks with similar goals and expectations. This is what Social Contract is about, and I think if people use it, people will get more enjoyment out of games of every type.