"Depth", or something
I'm fairly strung out from drinking too much caffeine this evening: Albertson's gave me free samples of Kenya coffee for buying my groceries on the web, so I sampled the samples while working late on an internal milestone, but the samples are lasting a lot longer than the work did. So I'll take the opportunity to post some embryonic thoughts I half-baked earlier in the week.
Although Maxis claims that certain games such as
SimCity and
The Sims are not games but toys, I do not believe this to be the case. Maxis defines games at activities having goals, so by their definition
Devil May Cry is a game (defeat all these creatures until you get to the end of the game) and The Sims is not. However, there is nothing in the dictionary saying that games must have goals in order to be games.
A recurring line of reasoning in game design is that a game should consist of systems of simple elements that, when combined, allow emergent strategies to develop. Richard Rouse III discussed this in
Game Design: Theory And Practice, citing the eyelets of Go, the forks of chess, the organisms of Conway’s Life. I have to agree. For me, finding these emergent strategies is one of the purest kinds of fun a game can offer, and it’s something that
The Sims and
SimCity give us in spades, but
Devil May Cry is somewhat lacking in. Which do you consider a game now?
Which raises an important point. Games don’t need to have this kind of fun to be successful, any more than they need directed goals. I don’t think anyone plays
Grand Theft Auto for the depth of gameplay; although it does have a few emergent strategies (do the taxi/cop/ambulance missions first, before the gangs get angry at you, to make the other sorts of missions either: that’s an example of a holistic strategy that emerges due to the properties of the missions.)
GTA3 is successful for different kinds of fun; its immersive qualities, its visceral intensity.
So we could use a name for this synergy-of-elements kind of fun. Let’s call it ‘depth.’ The more emergent strategies that come out of the simple elements of your game, the deeper it is.
A game that relies on emergent strategies for its fun is only fun as long as we keep finding new emergent strategies in them; finding the emergent strategy is the reinforcing stimulus—the food pellet—that keeps us playing the game.
Games that have cinematic storylines and unlockable goodies don’t need depth to keep a player playing beyond the point where they feel they’ve found all the emergent properties; a player will often continue playing to get to the ‘end’, to see the final cut scene or unlock some goody for which they have for some reason attached a fetishistic value. But if the storyline isn’t compelling enough, the game fails. And even if the first edition of the game succeeds, the sequel may fail simply because it’s more of the same. It suffers Version One-Point-Five Syndrome. Again, witness
Devil May Cry.
As a counter-example, the
Tony Hawk gameplay has so much depth that even though I worked on ports of
Tony Hawk I & II, minor tweaks to the system allowed me to continue enjoying III and IV for many, many more hours. So that’s my argument that, despite the number of shallow games on the market, it is still worth striving for depth.
We can get rough measures of depth in a couple of ways. One way is to compare the scores of beginning and advanced players. In games like
Chess and
Go, a moderate player can beat a beginning player almost every time. And an advanced player can beat a moderate player almost every time. And a grandmaster can beat an advanced player almost every time. It’s true for
Go,
Chess,
Tony Hawk, and
Kohan. It’s not so true for, say, Checkers; some games you reach a cap where there’s very little you can do to gain further advantages. (Of course, a game with 'breadth'--a wide set of rules that don't interact complexly but you have to know them all to have the highest advantage--could also have the same disparity in play-mastery. In some ways
Tony Hawk and
Kohan both fall into this category, each with their own large sets of special moves and heroes which the game mechanic requires you to know all of to be at the peak of performance.)
(A second, less useful, method that doesn’t so much measure depth but breadth times depth—how much there is to a video game in toto—is to look at the articles on it at GameFaqs.com. If they can describe all there is to a game in very little space (
Final Fight,
Panzer Dragoon Orta) then you can bet that the gameplay is shallow. If it takes a lot of space, then you’re looking at either a “stuff game”—lots of elements that don’t combine to form higher level strategies, such as
Diablo—or a depth game. Or both. Unfortunately, this after-the-fact measurement isn’t terribly useful when a game is in development.)
A combination of atomic elements that elicits emergent strategies is something any game can have, no matter what the genre. It isn’t just for strategy, fighting, and trick games. In these games, the player is left to discover the emergent strategies (should I call them emergencies? No.) themselves. But this theory works for puzzle games such as
Zelda and
Lode Runner as well. The difference is that here, the game designer thinks of clever ways in which the elements can create emergent behaviors, and purposely puts these combinations into the game.
For example, one atomic element of
Lode Runner—you can dig below you, to the left or the right—when combined with itself, creates the emergent property that to dig n blocks down you need to dig a pit n blocks wide, and thus can guide level design.
Some game designers disrespect puzzle games on the grounds that once you’ve solved a puzzle once the puzzle is no longer interesting. This is true, but fails to take into account the fact that once you’ve found an emergent strategy, that emergent strategy is no longer hidden, and your non-puzzle game is therefore that much less interesting as well. (To give the non-puzzle games credit, though, it’s much more likely that people will find strategies the game designer was never aware of, and therefore be able to get more enjoyment out of the non-puzzle game than the game designer consciously put in. This is not true of puzzle games.)
Even adventure games can be thought of in terms of atomic elements. A good example of this is
Day of the Tentacle.
Day of the Tentacle has the same engine as
Sam and Max, and yet is a superior game. Where in
Sam and Max, the puzzles are all of the scavenger hunt variety (find this item, use it here),
Day of the Tentacle provides a system that creates a whole class of puzzle, and then creates several examples therein.
Day of the Tentacle is about time travel; you have three characters in the past, present, and future, and a narrow pipe (actually a toilet) with which you can send some items forward and backward through time. The kicker? You can also send items through time by hiding them in a place to be found by your friend in the future. In this manner, you can bury a bottle of wine, and in the future you’ll have vinegar. You can leave a washing machine running on a sweater, and in the future you’ll have a sweater fit for a hamster. By providing the additional element of the chron-a-john, Dave Grossman and Tim Schafer create emergent properties that
Sam & Max could only dream of having. Their game design genius lies in recognizing that this one element would open up so much.
So how does one achieve depth? The answer, I fear, is the same answer we’ve heard all along: prototype, playtest, and iterate. Conway’s Life is a good example of this. The elements of life are cells that are either on or off; the interactions come from neighboring cells. There are five hundred twelve possible interactions for a given two dimensional cellular automata; therefore the number of possible rule sets we could create are two to the five hundred twelfth power. (That’s around 1E77; if you took a second to test each simulation, looking for emergent properties, it would take around 1E63 eons.) So Conway makes a good guess, and simplifies the problem by only considering population. A living cell with too few neighbors dies; a living cell with too few many neighbors dies; a dead cell with enough neighbors, but not too many lives. Now we’ve got a reasonable number of results to test. Still, with all these possibilities, only one is famous; the cellular automata discovered by Conway which he called the game of life, with its gliders, replicators, eyelets, clocks, and so on and so on.
Why is this one famous? If you play around with life (
http://psoup.math.wisc.edu/Life32.html is an amazing version of the program) you’ll discover that just tweaking the rules a little (making birth or survival one level easier or harder) leads to either massive overpopulation or boring stasis. (You’ll also discover that people who are into life are scary into it.
http://www.radicaleye.com/lifepage/lifepage.html)
So when making a game, we do what the life scholars do. We make some elements and some rules and then run the simulation to see what happens.
Still, prototype/playtest/iterate is not an ideal way to live. It doesn’t give us any idea when we’ll finally strike depth. It would be nice if we could find some tools to do it right the first time.
I don’t believe we can do it right the first time—without massive luck—but I do think there are some techniques we can use to reduce the number of iterations:
What is the matrix?
For puzzle and adventure games, coming up with rule sets, and for predicting what emergent qualities a game might have, we can use the programmer’s good friend: the matrix. Simply list the elements your game contains horizontally and vertically, mask off the bottom left triangle, and consider the interactions between each pair of elements. This should stimulate the creativity for thinking about puzzles and level design, give you test plans, and the like. Unfortunately, due to the limits of paper and the human mind, it’s not likely you’ll be able to carry this practice into matrices of three or more dimensions, where it’s possible you could discover some other interesting interactions. (The combo system from Spider-Man: The Movie, with its three-button codes for sets of attacks, could easily be expressed with a three dimensional matrix.)
Adding another element does not necessarily make the gameplay deeper
At first glance, it might seem like adding a new element will always make gameplay deeper. Hey, adding the time machine to Day of the Tentacle worked great, right?
But let’s take rock, paper and scissors, for example, where the gameplay is very shallow, with no emergent properties to speak of, and let’s add an element.
Everyone knows what happens if we add ‘gun’: the game is ruined. You laugh. But I would argue that Kohan (an excellent game despite this flaw, btw) was made shallower by the introduction of the Kohan units, as the special powers of these units unbalance the core rule set and mask the finer points of the game’s strategy. It goes from being a game of using your units to their maximum effectiveness to a game of knowing what special abilities all the Kohans have. Breadth kills depth.
So what if we try to add an element that is in balance with the other elements? Let’s call it ‘phleghm.’ We make a circle: phleghm beats scissors beats paper beats rock beats phleghm. When elements attack across the circle, it’s a tie. (Phleghm ties paper; rock ties scissors.)
After some playtest, we discover that Rock Paper Scissors Phleghm is no more fun than Rock Paper Scissors. In fact, we come to the sad realization that Rock Paper Scissors was a better game before we mucked with it; it was simpler, it was easier to remember the results table, there were fewer ties, and the hand signal for ‘phleghm’ was problematic.
Taking out elements can improve the game
Supposing we started with Rock Paper Scissors Phleghm. We could immediately improve the game by removing one of the elements. It doesn’t necessarily give us depth, but it can reveal depth, just as tuning the population curve in Conway’s Life can reveal emergent patterns.
This happened with Tetris. Originally the game was based on a puzzle with shapes made from five squares; when they simplified the shapes to ones made from four squares the game became, well, Tetris.
So Less is More seems to be a canonical rule of game design. This rule seems to exist in conflict with another rule of videogame design, which is: maximize the number of ways in which the player can feel like a hero. But of course it doesn’t really; if strategies really do emerge, then the number of ways in which the player can kick ass multiplies.
Okay, caffeine is finally wearing off. Good night.