A game’s depth can be defined as the amount of “stuff” that the player can learn about the game.
A shallow game has few things to learn. Think of when you first learned algebra. Because you didn’t understand the concepts of algebra, you would engage in a guessing game to find the value of x in simple expressions like “x - 10 = 3.5”. Not long thereafter, your teacher taught you that there was a method you could employ that could obviate the guessing: simply “undo” the operation on the left side and carry its effect over to the right side (“x – 10 + 10 = 3.5 + 10”). Now the guessing game isn’t a game anymore, it’s a rote task. If someone gave you 50 problems of similar complexity to solve, you would previously have had an interesting (debatably) task of excitedly guessing what x might be. Now that you know how to do it, you just mechanically run through the problems subtracting or adding numbers to both sides and receiving an result. There’s nothing left to learn there. So clearly simple algebra isn’t a deep game.
The scary part comes when you realize that you can think of World of Warcraft as algebra. You’ve got a few abilities that you can use and you’ve got enemies to kill. The first few times you fight, you’ll try different methods—essentially trying to guess the answer to “how can I make my relative DPS greater than theirs?” But once you’ve figured out a reasonably effective method, you no longer have to think. You only have to press 1-3-4-2-4-… until the enemy is dead or you are dead. The monotony is only broken when you move to a radically different kind of enemy (usually it’s a difference in magnitude of enemy DPS, so your remaining health will be the only thing to change between the old “easy” enemies and the new “harder” enemies) or when you level up and gain new abilities which may or may not actually impact this process.
Playing WoW through the course of one level doesn’t have much depth. The little bump in depth you get out of advancing doesn’t help for long, either. It’s just like learning that you can undo division with multiplication on the next homework after you mastered undoing addition with subtraction. Regardless of that bump in complexity, you still must solve those same problems (kill those same enemies) 50 times before the teacher will give you a passing grade and let you move on to the next-most-difficult homework (move on to the next level).
There’s a crucial distinction here: Depth is not the number of problems you could conceivably solve, it’s the number of conceivable techniques you could viably use to solve problems.
Players perceive these two different phenomena in MMOs and attribute both of them to the concept of depth.
In easy games like WoW, depth is artificially created through making enemies always too easy. Players are never forced to explore much of the game’s strategy space—even in the kiddie pool there can be a “deep end.”
This definition of depth only serves the “serious fun” or competitive style of gamer. To a casual player, such depth is just annoying. A casual player can’t spend the time to explore the strategy-space—he just wants to move inexorably forward and be tickled by something interesting occsionally as he receives a stream of ego-boosting rewards at a regular clip.
To the casual player, depth becomes the sheer amount of content. The casual player does not care about the advancement and evolution of strategies. They don’t want to have to think that much; games are distractions and ways to pleasantly pass time. Casual players only care that there is more to do—that the pleasant rollercoaster ride continues until he wants it to stop.
So we’re left with two definitions of depth that are useful when designing games for different kinds of players:
- Having more to do.
- Character advancement.
- Game as meditation.
- Relaxed play.
- “I must lay 300 more bricks to finish this wall.”
- Having more to learn.
- Personal advancement.
- Game as intellectual exercise.
- Serious play.
- “I must learn how to effectively approach enemy positions in Go to improve my early-game.”
Visualizing the Interactions of Depth
I see these two kinds of depth as two faces of a shape that represents the amount of fun that can be had in a game. Casual players look down one face of the shape, their depth is the shapes’ width, while hardcore players look down another face, their depth is the shapes’ height. The two are manifestations of different ways people enjoy games.
This means that games can be seen as two-dimensional objects in “depth-space”. The x-axis represents the amount of content completed, and on the y-axis is strategic understanding. Each shape represents the depth profile of the game—the width of the shape at a certain value of y indicates the amount of content that can be completed with that level of understanding; the height of the shape at a certain value of x represents the amount of knowledge that the player can gain having completed a certain amount of content in the game.
A game like WoW stretches a long way on the x-axis, but only gets high on the y-axis later. Chess, on the other hand, has a significantly taller shape, but there is not much width at any one point along the y-axis. This is because you have to engage with more of the strategy-space (learn more about the game) in order to unlock more content in chess. WoW is wider at all points on the y-axis because there is a lot you can accomplish with even a severely limited amount of strategic knowledge.
This visualization technique is not perfect. Aside from the general abstractness of it (a lack of metrics), it’s definitely not true that the two kinds of depth are orthogonal. Playing through more content usually increases your understanding of the strategy-space, which will gradually advance you along the y-axis naturally until you reach a saturation point that’s probably dictated by your intelligence.
These Depths Converge in the Long-Run
These two conceptions merge as the casual player plays the game more and must confront either the fact that the game is no longer stimulating or the fact that they cannot achieve their goals without digging deeper into the strategy-space. So games aimed at casuals do need to have some degree of traditional depth to sustain them long-term—though casual games are usually aimed at children and non-gamers—people who are not going to spend enough time in the game to hit the “no learning left” issue.