A game divided into shards has many different “copies” of the entire world running in parallel with different populations of players. For the purpose of this article I am talking primarily about the sharding mechanism used by MMORPG’s like World of Warcraft, Warhammer Online, Rift, etc. This is a hosting technology or method, and not a game design decision. Shards have been around for a while and are a simple method of handling lots of players.
Shards separate your players.
Ask anyone who has started playing a sharded game and they can tell you the problems of picking which shard to play on. Friend group A is on shard X and friend group B is on shard Y and a player will have to choose which group to play with. Dividing your players from all their friends means smaller groups and a higher chance that they will fold when a few people quit. A sharded game doesn’t have a single fifty thousand player community, it has ten five thousand player communities. And, if your game has factions, you might have twenty communities of two thousand five hundred players each. Each cut making the potential pool of team-mates smaller for the players.
Shards are inflexible.
When an MMORPG grows, or shrinks, shards get in the way. There is no smooth waxing and waning in population. As the population shrinks, shards need to be consolidated to keep each shards population healthy. As the population grows, new shards are added, yet new players want to play with friends already playing the game. Guilds and players are shuffled from shard to shard to try and keep populations dense. In practice, as populations shrink, several shards become desolate and empty of players. Even if the overall game community is a healthy size, the perception of the game being empty is a negative impact on the players. The reverse effect is having players wait too log in a queue because there are too many people on their shard. Even if shards can be added quickly, transfers of characters are still required to actually reap the benefits of shards.
The net result of shards is that the only method to “balance” populations across them is transfers. One possible solution is to make transfers between shards transparent, effectively turning shards into instances. Another options is to design the hosting system to scale without sharding. Sharding is another method of managing MMORPGs that is long in the tooth and should not be used any longer.