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Developing Multi-Player Games from Scratch
versus
Adapting Existing Single-Player Games
for the Multi-Player Environment
Introduction
Single-player games came first.
All the major games companies in the world got where they are today by producing
single-player games. There are, of course, a number of relatively successful companies
which have concentrated on multi-player games, the most obvious of which is Kesmai Inc.;
even so, the top 20 - perhaps the top 50 - computer games development companies all have
a background in single-player games.
Things are, of course, changing. Most of the major games releases you can buy in
the shops today, for the PC at least, have multi-player options (whether by LAN, modem
head-to-head, Internet, or all three). In many cases, the games have even been designed so
they're great fun to play this way. However, in the main they're basically the same, old,
single-player games with their AI modules replaced by comms modules. Lack of a multi-
player option reduces the scores that games are awarded in the all-important magazine
reviews, and, since it's not too so difficult to add a multi-player capability, developers
include such an option; whether the game is any good multi-player is not especially
important (although there are honourable exceptions).
My contention is that the way forward for multi-player games is to design them
from the ground up to be uncompromisingly server-based, multi-player, online games: the
multi-player games of the future should not simply be single-player games that allow extra
players. (Corollary: single-player games should not simply be multi-player games that have
AIs instead of other players, although that isn't what I intend to argue).
Note that I make a distinction between online multi-player games (which are what
we'll get) and peer-to-peer multi-player games (which are what we have).
Player Psychology
Online multi-player games make different demands on players to those made by
single-player games, or peer-to-peer multi-player games:
Players play for different reasons.
For single-player games, the chief source of amusement is usually puzzle-solving or
beating the game's AI (or, if it doesn't have one, its random-number generator and the
clock). For peer-to-peer games, the fun comes from beating other players; there may be
team play, but the goal is the same.
For multi-player, online games, the player wants a more rounded experience; people
are as important as gameplay. Some of these people will be enemies, and others will be
can't do this in peer-to-peer games.
Players stop playing for different reasons.
Single-player games lose their lustre for a number of reasons. They will usually be
played intensively after being purchased, but the player will quite often begin to find flaws
in the gameplay, or in the way the game's reality measures up to its pre-launch hype. Those
games which are well-designed enough to satisfy the player will typically occupy them for
some time afterwards, until the gameplay gets samey enough for the player to find playing a
chore. This will normally happen a few months, or, rarely (e.g. Civilization) one or two
years after purchase.
Peer-to-peer games have a fad-like quality. Everybody spends their lunch hour
playing multi-player Doom until they get bored, then they stop. Multi-player Quake will
probably go the same way. A group of people must all collectively want to play; it's an
aspect of the group's sociability, but it doesn't moderate their society. Online, multi-player
games hold on to their players for much, much longer (if the games are any good - or,
often, even if they're not!). Players will either leave after a few hours because they can't
get into a game, or they'll stay for ages. I have people playing my online games who have
been doing so for 9 or 10 years. When players do leave, it is often due to external factors
(new job, moving house, huge phone bill), but there is a fair degree of churn due to the
attitude and actions of other players in the game. If an environment ceases to be an
attractive place, the players will move out. If another environment appears which is more
attractive, they may also move out.
Players play at different times
Single-player games have no timing problems; players can play them whenever they
have the time. Peer-to-peer games have big timing problems; players can only have a
proper game when all the players are ready, and if they all want to play rather than go
down the pub for a game of darts.
Multi-player, online games have players coming in at all times. People can have
already been playing in a long session when someone else arrives, and unless the game is
designed to anticipate this the new player could be seriously disadvantaged. This enforced
variety is also a strength, however, in that it increases the depth of the game if components
of it have been especially created with this in mind.
Players play for different times.
Single-player games can be played in sessions lasting from minutes to hours. Peer-
to-peer multi-player games are usually of a fixed duration implicitly agreed upon by the
participants at the outset.
Multi-player online games are never-ending, and players play for as long as they are
having fun. Many will plan on having a session of a certain length, but how long exactly
they do play for varies depending on what's going on. Usually, they will either "pop in for
a few minutes" or have a definite goal in mind beforehand which could take them several
hours to complete. The provision of such goals is an important but frequently-overlooked
aspect of multi-player game design. Quite often, though, players will drop by just to see
what's going on; when this happens, you know your game is a success.
death. For single-player games, this does not matter; competition is only verbal, of the
"your top score is only 115%, ha ha ha" variety. For peer-to-peer games, it does matter;
the inexperienced player will be ritually slaughtered.
For multi-player, online games, it has not to matter. If it did matter, the game
would not appeal to new players. There are a number of strategies for ensuring that
newcomers aren't put off by the show-off antics of other players, ranging from off-line
training sessions to hard-coded newbie protection schemes. As a cautionary note, it must
not be the case that experienced players are handicapped to an extent that gives novices a
huge advantage; rather, the aim is for old-timers either to take new players under their
wings, or to be completely unconcerned by them.
Different numbers of players play.
It may seem obvious, but there are differences in the way that players treat games
which have more than one player. Cheating in a single-player game is fine if you're the sort
of person who can justify it to yourself; it is not fine in multi-player games, and must be
dealt with ruthlessly.
In a big, online world there could be 300 other players playing at the same time; this
gives the world a bustle that leads to an entirely different gaming experience, and players
are likely to have to choose their activities in the light of what else is going on, rather than
simply what they want to do.
Constraints on Games
The above issues are reflected in a number of constraints which must be borne by
multi-player games.
Technical.
As has already been mentioned, there is a distinction between those multi-player
games which are server-based, and those which are peer-to-peer. The latter are the logical
extensions of single-player games, and are the type of multi-player game we see on the
market at the moment. They don't need a massive amount of computing power, because
they don't deal with the kind of numbers of players that online games do. Also, because
they use game engines and libraries developed for the single-player market, they can be put
together much more easily.
Multi-player, online games do need to be fast; when a command comes in, the
player wants it processed now. Sometimes, there are periods when few commands come in
(during which time background tasks can be performed), but at other times a whole bunch
of commands can come in simultaneously and the machine has to be able to deal with them
expediently. Fortunately, the grunt graphical work can be done by a client at the user end,
although unfortunately that does mean two separate pieces of software are required to talk
to one another, and only one (the client) uses a great deal of software already in developers'
toolboxes.
Robustness and reliability.
Single-player games can crash, which is just as well because many of them do.
LAN-based games can crash; in doing so they cause groans among the players,
but they're easy enough to restart, and it's not as if anyone would be losing
the fruits of hours of effort as a result.
Multi-player, online games can't crash. If they do, many people will be
inconvenienced, and they'll all complain together. People may have been setting up their
position for an hour or more, and although their score and character stats will normally be
saved as the game tumbles over, their overall situation will not be, nor could it ever be
because it's relative to the other players. People are seriously annoyed when a multi-player
server-based game goes down, unless they have been sufficiently warned beforehand that it
is going to happen.
Depth and lifetime.
Multi-player, online games are played over a very long period of time, principally
because of the ties of the community which develops. However, they must have enough
in-built gameplay to support this; talkers have a much greater churn than games, as there are
no "events" happening. Because of this, online games typically have to be more open-ended
than single-player ones: they need to have more options available, and to be able to address
specific types of users such as newbies, old-timers, people who want to play all evening,
and people who want a 15-minute diversion over their lunch hour. As mentioned earlier,
though, it is often the case that by facing up to the issue of having different player types, an
increased game depth follows; this in turn can lead to a more satisfying gameplay.
The main point where many single-player puzzle-based games fall down is
replayability. It would be perfectly possible to program a How to Host a Murder style game
online, but people could only play it once. Worse, measures would have to be taken to stop
people who had played it before from playing it a second time, so they wouldn't spoil it for
everyone else. Puzzles in an online game are perfectly OK, but they should be
comparatively numerous, of varying degrees of difficulty, and very much secondary to the
problem-solving required as a result of the activities of other players.
Genre.
Certain types of game cannot be successfully implemented in a multi-user
environment, particularly those involving time travel or the destruction of shared resources.
Many games of a risqué nature are also often best played in private... Complicated
narratives don't work well in multi-player games, which tend to thrive by offering a free
choice between many courses of action. Also, by virtue of the fact that many people want to
play at once, the genre has to be popular: SF and Fantasy dominate.
Size of world.
The playing area of a single-player game does not have to be huge; even a few
hundred squares or hexes or whatever can seem vast. In multi-player games, it's the
population density which matters: too few locations per player and it feels impossibly
crowded; too many, and it ceases to spark enough interaction to be truly multi-player. This
isn't too important in peer-to-peer games, where the number of players won't exceed some
fairly low value like 8. It is important in online games, though.
If the number of players in a game is likely to fluctuate wildly, it's best if the game
is self-regulating, allowing areas to open up or close down depending on how many people
are in it at the time. Thus, when it's 2am and only 20 people are playing, the quests
Single-player games have a winner. Peer-to-peer games may or may not have a
winner, but they're certainly competitive. Multi-player online games do not have a winner.
There may be some status level beyond which progress cannot be made, in which case the
player can be said to have "won", but that doesn't mean other players can't win later.
Consideration of the final "goal" of a long-term, multi-player game is something which
needs to be built in to the design at the very start.
It is possible to have winners for session games, which are usually of the Space
Opera "conquer the universe" theme. These would typically have a lifetime of, say, 3
months, and many of them would run in parallel with different start dates. This works best
with play-by-email or "batch play" games, however, and suffers badly from player dropout
if they see their situation as untenable. Thus, teams of players tend to be encouraged, so
lots of people "win" when it finishes.
Player pool.
Online games each want a slice of the player cake. However, if one game takes a
big slice, the other games have to lose a piece off theirs, and some may get none at all. It's
made worse in that games need a critical mass of players: below a certain number, everyone
will stop playing and the game will be dead. This is not a problem with single-player
games, of course. Although multi-player games can provide interesting things for people to
do if they are alone, rarely is this enough to keep them occupied for hours (because if it
were, the game would effectively be two games combined, one single-player and one multi-
player).
Legacy Design
The way that games are written at the moment, players and network providers
unwittingly conspire with developers to maintain the single-player paradigm. Players do get
multi-player options for the single-player games they buy, but they don't get the kind of
multi-player experience which causes all the fuss that made them want a multi-player option
in the first place.
There are several levels at which this operates:
What players say they want doesn't necessarily mean they do want it.
People will passionately advocate something in order to seem hip and trendy (or to
show that they remember the old days when games were great and computers were 8-bit).
The former, bandwagon effect is the one which developers pay attention to, because if they
jump on it then they can be seen as a progressive outfit. Hence, developers hear what
gamers say they want, then give them it whether they really want it or not. The worst
offence is to be old hat; this is what killed off text adventures.
Players will say they want something because its very premise is interesting,
although when they see the finished product they may decide otherwise.
Multi-player games fall into this category, in that the idea of playing other people is
very attractive, but it may not necessarily turn out to be quite so nice when the only people
you can beat are aged under 12. The trick is to isolate what it is that
people like about an idea and implement that, rather than implement something
which fits the general category. Even then, the results can be discouraging:
people may genuinely like the idea of seeing a game in stereoscopic 3D, but
when they try on the headache-inducing glasses they may
defer buying it.
There are some things that players really do want, but which they won't believe
they actually want until they are forced to experience them.
In many respects, MUDs are like this. Whatever the Internet killer application
finally turns out to be, the chances are that at the moment people don't know they want it.
What the developers can realistically provide, 2 years down the line, is based on
what they can do now. Now, they can write single-player games, and design them in such a
way that they can be played by a limited number of extra players instead of AI modules.
That is therefore what they provide; however, it's still basically the same, single-player
paradigm.
The problem is that writing single-player games is not like writing multi-player,
online games, and the peer-to-peer games we're getting at the moment, while good in their
own right, are nothing like the online games that are going to make pots of money.
To use an analogy, we're asking people who design speedboats to design passenger
liners. There are many similarities, but in general you don't design a passenger liner by
taking a speedboat and adding more seats. What's more, if you did that, you'd lose a lot of
what's fun about a speedboat.
Some of the features which give single-player games an advantage over multi-player
ones (turn-based strategy games, narrative-driven adventures, high-tech defender against
hordes of low-tech attackers) are nowadays ditched at the design stage so that a game can be
made multi-player. This means that in the quest for multi-player capabilities, sadly we're no
longer getting the variety of single-player games we used to get.
The way to design a passenger liner is to design it from scratch as a passenger liner.
Product Support
Online games are a commitment.
With a single-player game, you finish it as close to the deadline as possible, you get
a distributor to sell it, you take your money, and you reluctantly send out patches to correct
major bugs. You have a help-line and a web page for people who wish to bother you,
staffed by trained personnel who can answer questions about all the games you carry while
play-testing your new ones.
Peer-to-peer games follow exactly the same path.
With an online, multi-player game, you get your basic, stable version working, and
you make it available. You take your money, and you continue to do so while people play
it. However, you have to ensure that bugs are fixed very quickly, and you have to improve
the game gradually so as to add the depth it will come to need. Your support staff are
people managers who spend all their time logged in to the game ensuring that the players
are behaving as they are supposed to behave, and acting as cheerleaders to encourage people
to play more often than they otherwise might.
These people-managers are also dedicated players. This is good, because it means
there is always someone playing in the game. Nothing puts people off more than an empty
multi-player world: there may well be 50 people waiting to play just as soon as
someone else appears, but, if no-one does, they don't.
Revenue
The main sources of income for a game are:
- selling the software needed to play it
- charging people to play it
- merchandising
- sponsorship/advertising.
The key factor which multi-player online games have that single-player or peer-to-
peer don't is the ability to charge people money every time they play. In the publishing
world, this would be like printing a book and taking a royalty every time someone read it.
With peer-to-peer games, the per-game charging is either non-existent, goes to the
telecommunications company, or goes to a gamer introduction service. This is fine if you
are the telecommunications company, but if you're not then you're going to the trouble of
making your games multi-player but someone else is making all the money that follows
from it. In fact, it's worse: if people are still playing your last game when you bring your
new one out, will they want to spend money on this new one?
Note that games which are only played once are no good as online games. Returning
to the How to Host a Murder analogy, it would take you forever to recover the development
costs for an 8-player game, even if the players paid premium rates (£10+ a session) and the
game engine could deal with a large number of pre-written scenarios.
Multi-player games can still sell as boxed units. When Air Warrior was launched in
the UK, it made practically all of its money from sales of boxes. Roughly speaking, for
every 200 units sold, 1 player actually tried the game out. That was four or five years ago
now, though, and things have changed somewhat. Nevertheless, Meridian 59 still manages
to bring out client software at £39.95 a pop. Whether they'll make money from their online
charges remains to be seen, but the chances are they will do rather well if the game has
enough depth.
Server-based games will therefore win out in the long term, because they have a
revenue stream unavailable to single-player games: pay-to-play. Like pay-per-view TV, if
the quality is there, people will indeed reach for their credit cards. The market will
eventually become saturated, of course, but that will only serve to increase the quality of
what's available as true competition takes over. It will take a long time to reach full
capacity, though: the current list of publicly-available MUDs has 675 games on it, whereas
last year at this time it had 538; the actual total is probably 50% more than this, and these
games aren't even professional quality.
There'll still be a market for single-player games, because they're a different breed;
the single-player market may even remain a bigger market than that of online games.
However, will I be able to find someone in 5 years' time who will want to play multi-player
Warcraft II with me? Probably not. Will I be able to play Meridian 59? Probably. Will I be
able to play a text-based MUD? Definitely.
Conclusions
The multi-player
games which are going to make money are the ones that
have a server, because they are the only ones which can keep players playing
and paying for years and years and years. Peer-to-peer facilities in games
may sell marginally more boxes, but
they're one-off payments by the customer. It would really, really help if Wireplay and their
ilk could pay royalties, but can they?
Single-player or peer-to-peer games will still be around and will still sell like they
always did.
Those developers who think they will gain all the benefits of a multi-player online
game by merely adding multi-player capability to games designed for single players are
mistaken. Such a feature may be all well and good as a means to stop writers from games
magazines complaining about if it's missing, and it may sell you a few more units, but it
won't generate a revenue stream.
Those developers who think they will gain all the benefits of a multi-player online
game by designing in a multi-player option into their game from the beginning are
mistaken. It's not an option, it's a defining quality! It might give you better head-to-head
play, which could keep people interested in the game for some time, but will it sell you
more units? Or will the fact that people are still playing your old games mean that they'll
see less reason to go out and buy new ones?
In the long term, server-based games are going to make some people very rich. In
the short term, developers are going to continue to add multi-player options for "Internet
play" to their products and wonder what all the fuss concerning Internet games is all about.
Two things will remedy this:
- The success of risk-takers. Meridian 59 is a first step, but it's not a marvellous
game. Ultima Online will probably be the turning point.
- Time. Developers will eventually work all this out for themselves,
especially those who attend conferences such as this one and have it all pointed out to them..!
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