Replayability
Part 2: Game Mechanics
By
Ernest
Adams
Gamasutra
July
3, 2001
URL: http://www.gamasutra.com/features/20010703/adams_01.htm
Last month I looked
at the way narrative affects game replayability. This time I'll be looking at
how replayability is affected by the game mechanics themselves.
Obviously, the
single most important contributor to a game's replayability is its playability
in the first place. If a game is badly balanced, if it has a poor user interface,
if it seems to be lacking essential features, then it's not going to be much
fun to play, much less to play again. But there are specific design considerations
that influence a game's re-playability, and those are the ones I'll be talking
about here.
Let's start with your basic single-player computer game. Whether a player perceives such a game as replayable depends to some extent on what kind of a player he or she is. Consider our two old friends, the core gamer and the casual gamer. (See my earlier column, "Casual versus Core" for a discussion of these folks.) Since a core gamer's primary motivation is beating the game, as long as the gameplay is interesting and above all challenging, he will continue to play that game repeatedly until he has beaten it, even if the gameplay is very similar every time. The core gamer has no problem with a game like Pac-Man, because even though Pac-Man is a deterministic game that behaves exactly the same way every time you play it, it offers a huge amount of gameplay. Pac-Man contains 256 levels, and very, very few people have ever played them all. The core gamer doesn't mind a game that plays the same way every time, as long as he's got an entertaining challenge to overcome.
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Pac-Man
contains 256 levels, and very, very few people have ever played them all.
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This is why arcade
games are designed for core gamers, and why they make so much money. Most arcade
games provide large numbers of levels and progressively increasing difficulty,
and many have deterministic gameplay. The deterministic gameplay allows the
core gamer to move swiftly through the early, easy levels, and get up to the
harder ones where the real challenge is. Most arcade games are also ultimately
unbeatable; they simply get faster and faster until no human being could possibly
keep up with them. This means that the object is not actually to beat the game,
but to beat your own personal best score, and that's something you can always
try for no matter how many times you have played the game. Core gamers give
up on arcade games once they become tired of the gameplay or they reach a point
beyond which they simply cannot improve, and once a core gamer does beat a game
once and for all, he's seldom interested in playing it any more. The pleasure
comes from winning, and since he now knows how to beat it, the challenge is
gone.
The casual gamer, on the other hand, plays not for the exhilaration of victory, but for the joy of playing the game. It's not enough to simply supply the casual gamer with a tough challenge and let her go at it; she has to be having a good time, and to lure her back again, one thing the casual gamer needs is variety. The game has to be different the next time she plays it.
Sources of Variety
Variety in a game
can come from several places:
Varying initial
conditions
Most
simple board games like chess, checkers and backgammon start with the same initial
conditions every time. Both players have the same number of pieces, placed in
symmetric positions on the board. But not all games require absolute symmetry.
In the board game Stratego, for example, the players start with equal
numbers of pieces of equal strength, but they may set them up in their own areas
of the board any way they like. This freedom in the initial conditions creates
variety for the players.
Initial conditions
can also be established randomly; this is of course the basis of most card games.
The deck is randomized by shuffling, and then a certain number of cards are
dealt out to each player. Bridge and hearts are good examples of card games
that depend entirely on varying initial conditions for its gameplay - all the
cards are dealt out, and the players play them as they best see fit.
Chance as a
part of gameplay
Even if
the initial conditions are identical, a game can include random elements as
part of the rules of the game. Backgammon and Monopoly are good examples
of this. The pieces start in identical positions, but their movement is determined
by throwing dice.
Any card game
in which you draw cards from a shuffled deck in the course of play (gin rummy
and most forms of poker, for example) is using both random initial conditions
and randomness during gameplay to create variety.
Non-deterministic
opponents
In a
game like chess, with identical starting conditions and no random elements,
what provides the variety is the opponent's gameplay. This usually (but not
always) means that a human being is a more interesting opponent than a computer.
Computers tend to be programmed with deterministic, number-crunching algorithms
to find the best move, according to some metric for measuring the quality of
a given move. With a deterministic algorithm, a computer program will always
choose the same move in a given situation. In time, human players can learn
to take advantage of this predictability; they also tend to find it rather dull.
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In
a game like chess, with identical starting conditions and no random elements,
what provides the variety is the opponent's gameplay.
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Human opponents
are more interesting because in addition to having varying strategic and tactical
abilities, they differ in the degree to which they're aggressive or defensive,
devious or forthright, cautious or risk-takers. And of course, you can talk
to them. There's a social aspect of playing against other people that is completely
absent when playing against a computer, and that tends to make the game replayable
even if nothing else does.
A choice of
player roles and strategies
If a player can
play a game in several different roles, the game will feel different even if
its content is the same. The character classes, races, and alignments in Dungeons
& Dragons are a perfect example of this sort of thing. You might play
an entire computer game as a lawful good human fighter, then decide to replay
it again as a chaotic evil elf magic-user. Although you encounter the same people,
creatures, and dangers the second time around, your approach to dealing with
them will be significantly different, especially if the designers have constructed
obstacles that can be overcome by a variety of methods. (Unfortunately, in far
too many role-playing games the only method available is "whack it until
it's dead." But at least there are a variety of ways of whacking it.)
Sheer size
You
can play an enormous game like Baldur's Gate from beginning to end and
still not see every location or undertake every quest, particularly if you concentrate
on the main storyline and don't allow yourself to get sidetracked often the
first time through. This gives Baldur's Gate considerable replayability.
It's just so big that it's worth going back and playing again to follow up on
adventuring opportunities that you missed the first time around.
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You
can play an enormous game like Baldur's Gate from beginning to
end and still not see every location or undertake every quest.
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Other Considerations
The most consistently-replayed
computer game in the world has got to be Solitaire, the version of Klondike
that is included with Microsoft Windows. So what's its appeal?
Some of these
characteristics are helpful to us and some of aren't. Item one, for example,
isn't much use. Most of us want to design new games, so computerizing existing
games from the real world doesn't have a great deal of appeal to us as designers.
(It can have a great deal of appeal to those of us who are AI programmers, however.
Many existing games make interesting programming challenges - chess is an extremely
simple game, with no randomness and no hidden information, but look how much
money has been spent on chess programming!)
Item five, too,
doesn't help us much. There's not a lot we can do about the fact that Solitaire
is free. Most of us want to get paid, so our games have to sell, and that means
that there has to be enough content in them for players to justify opening their
wallets. Unfortunately, content is expensive to make, and it often lengthens
and complicates games. There's an interesting relationship here, one that I
think we can learn from: the most replayable games are also the smallest
and cheapest to implement.
Items two, three,
and four get to the heart of the matter. Summed up in one word each, they are
simplicity, shortness, and ease. Trip Hawkins, the founder
of Electronic Arts, used to insist that games be "simple, hot, and deep."
Simplicity and depth (i.e. subtlety or variety) both contribute to replayability.
By "hot", he meant exciting, which is neither here nor there as far
as replayability is concerned; it helps if that's the sort of game you like.
Solitaire isn't very exciting, but it's still highly replayable.
Personally, I don't think Solitaire is a very interesting game. It's too random. You lose far more than you win and no amount of thinking you can do will change that. Free Cell, which also ships with Windows, is a much better game. It takes a little longer to play, but it offers a mental challenge that Solitaire lacks. Its rules are almost as simple and its user interface is identical. And unlike Solitaire, Free Cell rewards patience and persistence; it isn't that hard to solve to begin with, and in fact all but one of the 32,767 deals of Free Cell can be solved with enough effort. The knowledge that it can be done encourages you to continue to try.
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Replayability
requires a simple, compelling, addictive challenge and the most natural,
frictionless user interface possible.
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Designing for
replayability is the purest test of the game designer. Replayability requires
a simple, compelling, addictive challenge and the most natural, frictionless
user interface possible. All the big, expensive, fun things that we think game
development is about - spectacular graphics, hundreds of unit types, fifteen
different camera angles, and voiceover narration by Patrick Stewart - are irrelevant.
The game is reduced to its barest essentials: the challenge and the means of
overcoming it. If I were trying to design a game for high replayability, I might
actually start with cards or dominoes, something I can shuffle around on a tabletop.
They wouldn't necessarily end up as cards or dominoes in the game; they could
end up as genies or giant worms just as well. Their surface appearance doesn't
make much difference as long as the gameplay works.
Conclusion
Replayability
is not an absolute necessity for computer games. As my friend Jeff Wofford at
Deep Red Games points out, many games offer so much gameplay - forty or fifty
hours is not uncommon - that a lot of players don't even finish them the first
time through, much less play them again and again. If we've given our customers
an enjoyable time for a dollar an hour or so, we're doing pretty well; certainly
better than the movies do, even if our customers only play the game once. If
I were designing a large game, I probably wouldn't worry about it much.
Still, the question of replayability is one that every designer should ask herself in the initial stages of game design. All players, casual or core, want good value for their money. If the game can be played to its conclusion in a few minutes or hours, then you had better either set the price accordingly, or make sure that it's replayable by design.
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