Game Development Reference
In-Depth Information
Playing games over a network, especially the Internet, presents the designer with
certain disadvantages, as well. This section discusses some of these technical chal-
lenges, as well as the ongoing responsibilities of providing new content and customer
service. You should also be aware that strangers playing your game anonymously
over a network can cause social friction and that this can range from minor misbe-
havior to serious criminal offenses.
Technical Issues
Although this is a book about game design rather than programming, you need to
be aware of certain technical issues for online games that local games don't have
to address. This section doesn't go into them in great detail, but aims to make you
familiar with these technical considerations. If you design an online game you will
need to discuss them with your programming team.
COMMUNICATION MODELS
Your programming team will need to choose a communication model from the t wo
currently in use in networked gaming. In the first,
client/server
, each player runs a
program, called the
client
, on his computer, that communicates with a central program,
the
server
, on a computer owned by a company providing the game service. In the
client/server model, the server runs the game engine, sending packets of information
to the various clients, and the clients merely present that information to the players.
The other model,
peer-to-peer
, involves direct communication between the players'
computers. Implementation of peer-to-peer (sometimes abbreviated P2P) communi-
cation is quite straightforward for two-player games but becomes more complicated
as more players are involved. The players' systems must decide which machine to
designate as the
host
—that is, which will control the game while the others become
guests
. If the host logs out of the network, one of the guests' computers must take
over and become the new host—preferably automatically and without anyone's
noticing (this is known as
automated host migration
, a feature already supplied by
Microsoft's DirectPlay facilities). Some companies also operate
matchmaking
ser-
vices in which the company's server functions only to allow players to find one
another and connect together in peer-to-peer networks. All of this is programming
work that offline games don't have to bother with.
LATENCY
The Internet is designed for redundancy rather than speed, so it doesn't make any
guarantees about how long a given packet of data will take to get from one point to
another. This phenomenon is called
latency
. In many games, a faster connection
translates into a gaming advantage, making players with high-speed connections
more likely to win the game. You can design around this by making your game
