Last week I tried to define game balance. I came up with something that seems like a useful idea on how to make a game fun and I think would be positively correlated with people calling a game balanced... but it wasn't a good definition of game balance. The comments were very interesting and I had another talk with people this weekend on the topic to try to nail it down a little better. We started off talking about what sorts of games we would call imbalanced and going from there. Note that although balance and fun are linked I am not talking here about what makes a game fun but rather focusing on balance itself.
Ziggyny, who is the best Vegas Showdown player I know, says that he thinks it is an unbalanced game. He thinks this because the best strategy is to try to build the Theatre but that strategy requires the Theatre to come out. Most of the time it does but if it does not then the Theatre strategy simply loses and if it does the Theatre strategy simply wins... assuming people don't buy it from you for spite, which they sometimes do. All this is assuming good play and knowledge from all players. I would agree that a game where you play for a long time making many complex decisions that seem relevant at the time but which will be randomly determined to be relevant or not near the end of the game is unbalanced.
WOW is a particularly balanced game. When I say this I wonder what exactly it would take to make me think it was imbalanced and I think the primary thing that would make me think that is if the classes were not all balanced against one another in effectiveness. If the individual specs were not comparable in effectiveness I would note that as a lack of balance but much less so than classes. I don't think that particular styles like Melee Hunter or Naked Paladin need to be any good at all for balance to be achieved.
Settlers is a balanced game. Although there is a fair bit of luck involved (which you can limit substantially by using a deck instead of dice) it is definitely clear that better players win the vast majority of the time, weaker players have a chance to win and the sorts of things that you would think would make you win the game do in fact make you win the game. Being a canny trader, using intimidation/stalling/lying to get people to do what you want, placing settlements/cities carefully, making good decisions on when to crush resources, when to keep a big hand or dump your cards and who to hit with the robber baron all have a substantial impact on the game along with the aforementioned luck.
We also talked about if War is a balanced game. The conclusion we came to was that War was not a game at all since there were no player decisions of any kind and the result was decided purely by a complicated coin flip. Rock Paper Scissors seems like it will never be called imbalanced, it will often be called balanced and you might well call it 'too trivial to be balanced or not'. Either way it definitely does not trigger the 'this is unbalanced' feeling.
Puerto Rico is a mostly balanced game. When my group of friends plays we tend to bid for various seats since seats with corn have a starting advantage. The advantage is small in a group where people accurately recognize and attack the leader but nonetheless it is there. The feature that after a totally randomized start some players possessed a noticeable advantage was something we all felt was unbalanced. Clearly the game is a lot of fun without bidding for seats but there was a clear consensus that bidding for seats to achieve a more equitable start position made it feel more balanced to expert players.
So what is the common element in these things? Randomness is not considered unbalanced or balanced consistently, dependency on skill is not the determining factor and number of optimal ways to play does not seem to be the answer either. The common element I find is that a game is considered unbalanced if the primary driving factors behind performance and success are not what the players intuitively feel they should be. In Settlers people seem to feel that all the decisions made in the game should be impactful but luck should change the course of the game and occasionally have an overwhelming effect. People also feel that poker is balanced due to that same combination of skill and luck - the result matches their intuition. I think this also explains WOW nicely since it is a game where huge amounts of time are invested into a character so people tend to object to any choice they cannot reverse being too significant a factor in determining their power.
This isn't a definition I am in love with. I don't like the ephemeral 'what players intuitively feel they should be.' part of it and I wish there was something more concrete, more measurable I could use instead. Clearly we can measure specific things like "Do Ret Paladins do as much damage as Elemental Shaman?" somewhat reasonably but I don't think we can actually determine anything about whether or not a game is balanced until we ask people what they think should determine how successful and/or powerful they become while playing it. So here you have my brand spanking new definition:
A game is balanced if the primary driving factors behind performance and success are what the players intuitively feel they should be.
Now we can see if this one holds up better than the last!