[In this much-referenced technical piece originally published in Game Developer magazine late last year, the team behind idiosyncratic MMO success EVE Online discusses precisely why sharing a single world between all of its players makes sense.]
Most of the larger massively multiplayer online games use separate instances, or shards, of the game's universe in order to manage player populations and server issues. We feel that a single shard should be the natural choice of any MMO developer, and that's what we do with EVE Online.
When you ask the question "Why a single-sharded architecture?" it's also informative to look at the deeper question: "Why have shards?" There are two main reasons why a developer chooses a sharded implementation of a game -- lack of content and technical challenges. These are actually inter-related.
Most current MMOs take place in environments essentially limited by strong physical constraints: avatars moving across earth-like landscapes or within enclosures like buildings. Furthermore, within these specific environments, players are confronted with a multitude of scripted activities such as quests and NPC encounters that only take place there.
The most limiting physical constraint concerns avatar density. This is both a technical problem and a usability problem. Players do not want to constantly navigate an overcrowded environment. In order to keep avatar density within reasonable limits, you either need a very large playing field or a limitation on the number of players in a given field. Both of these options are restricted by the amount of content you can design, and since content is the biggest cost in modern games, this quickly becomes a financial limitation.
The obvious solution is to have procedurally-generated content, such that you can essentially have a playing field as large as you want. The drawback with that approach is that you will most likely never reach the same artistic level displayed in hand-crafted environments, and scripted activities might become repetitive and lack context.
The real solution to this problem is to embrace the notion that in an MMO, just like in any other social network, players are the content. Once that is accepted as a fundamental design guideline, it becomes easier to navigate the challenges involved in creating and maintaining a single shard architecture and actually gives the advantage to that design model.
Looking more closely at this assumption, we can identify two types of content generated by people: material content, which we describe as persistent user-created assets within the world, and social content, here considered as persistent patterns of social interactions.
The first one is easy to comprehend. However it is implemented, persistent player-created content can populate large playing fields and make the world more "meaningful" for large groups of other players. This is the case in RTS games, where the backdrop may be relatively bland and automatically generated.
In EVE, for example, a lot of the high-end gameplay revolves around conquest and control of territory in unregulated areas of the map. By choosing where to place primary space stations, players shape the topography of the strategic battlefield. In selecting the position of those stations' supporting starbases and the configuration of their offensive and defensive systems, they shape the tactical context in which critical battles occur.
The second type of content, social content, is the most potent, but also requires careful design. The field of social interaction encompasses a very wide range of activities and concepts:
With socialization, the main "content" is the social tapestry that materializes in buddy lists, membership of player associations, or guilds and forums. For all of these, a single shard adds to the richness of the content because players don't need to be split between servers; they can discuss issues and share experiences that arise in the shared world that are relevant to the whole player base rather than a specific server -- essentially giving them a shared history as a whole society rather than a disjointed one based on smaller server populations.
Furthermore, gaining fame becomes much more rewarding due to the size of the audience, thus strengthening the impetus to do so. The technical challenges to creating a single shard communication infrastructure should not be underestimated and we address them later in this article.
As part of CCP's efforts to nurture the development of the functioning society formed by EVE's player base, a democratically-elected player council was formed to act as representatives of player interests in the development process.
The single-sharded nature of the game enables the formation of a single coherent society and makes it much more likely that the elected players will form a representative cross-section of the interests of the electorate. Because everyone is sharing a single server, and thus a single social context, the community has a common baseline for discussion and debate, and famous figures are more likely to be known to the entire player base rather than just fragments thereof.