Two key concepts in games are having a goal and getting quick feedback. These concepts are useful for games, businesses and governments. Posters are a way to gently remind yourself of your mission, your goal, of who you are. But, posters, feedback and goals are not enough. They are all superficial. The most important things are having a team who can resolve conflicts, not having too tight controls on people and basically not allowing behaviour that is not valued by the group - this includes client behaviour. Only when these things are in place, or starting to get in place, do posters, the environment and the office matter.
Although... in real life we shape our environment and our environment shapes us. We have a value, then we write it down, then we stick it up on the wall, then we have another idea. All I mean to say is that posters (and dogs under desks) do not a start up make. If only.
Posters at CS