i will quote wikipedia for you... maybe this should become a sticy, REALLY.

Quote:

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Developing MMORPGs

In general, the cost of developing a commercial MMORPG title exceeds ten million dollars.[19] These projects require multiple disciplines within software engineering, art design and network instrastructure:

* The front-end (or client) component of a commercial, modern MMORPG features 3D graphics. As with other modern 3D games, the front-end requires expertise with implementing 3D engines, real-time shader techniques and physics simulation. The actual visual content (areas, creatures, characters, weapons, spaceships and so forth) is developed by artists who typically begin with two-dimensional concept art, and later convert these concepts into animated 3D scenes, models and texture maps.[20]

* Developing an MMOG server requires expertise with client/server architecture, network protocols, security and relational database design. MMORPGs include reliable systems for a number of vital tasks. The server must be able to handle and verify a large number of connections; prevent cheating; and apply changes (bug fixes or added content) to the game. A system for recording the game's data at regular intervals, without stopping the game, is also important.[21]

* Maintenance requires sufficient servers and bandwidth, and a dedicated support staff. Insufficient resources for maintenance lead to lag and frustration for the players, and can severely damage the reputation of a game, especially at launch. Care must also be taken to ensure that player population remains at an acceptable level by adding or removing servers ("shards"). Peer-to-peer MMORPGs could theoretically work cheaply and efficiently in regulating server load, but practical issues such as asymmetrical network bandwidth and CPU-hungry rendering engines make them a difficult proposition. Additionally, they would probably become vulnerable to other problems including new possibilities for cheating. The hosted infrastructure for a commercial-grade MMORPG requires the deployment of hundreds (or even thousands) of servers. Developing an affordable infrastructure for an online game requires developers to scale to large numbers of players with less hardware and network investment.[22]

* In addition, the team will need to have expertise with the fundamentals of game design: world-building, lore and game mechanics,[23] as well as what makes games fun.[24]

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