People who play games are people who need something to do. More often than not, communities are formed for games that are based on party systems (multiple users playing together).
The need and goal for the community ends there itself. People have a reason to engage. They have a need to look for co-players.
Besides that they also have a lot of questions about the intricacies of the game. This thing is easily resolved by community members.

On the other hand, community members are active and loyal because they have experienced the difficulties of fending for themselves alone, firsthand. They need assistance always, so they will assist always in return.

When creating communities, identifying the need and goals of the community is vital. Without it, you are definitely going to be aimless.
That's what I learnt, being a community manager for multiple games and what I wish to share with people who are unfamiliar with it.