Content Scaling in Role-Playing Games

Should this bear be statically determined, or dynamically scaled to the player's level?

Note: This article currently only addresses content scaling as it relates to a limited number of games, and focuses primarily on the Elder Scrolls series (Arena, Daggerfall, Morrowind, Oblivion, and Skyrim), and Fallout 3, so the discussion may be somewhat skewed. I hope to address the inadequacies of the article over time by testing these hypotheses in other games. These are simply the games that I happen to know best. Also, for the purpose of this article: level scaling = content scaling.

One of the challenges facing developers of open world games like Skyrim, Oblivion, and Fallout 3 is how to balance the player's experience in the game world. In a linear game, the player's movement is strictly controlled, allowing the developers to scale enemy difficulty and player rewards very precisely to maintain game balance. In an open world, where the player is free to explore any area of the map at any time, it can be difficult to provide players with an experience that is:

In this article I'd like to take a look at some of the different design choices that developers like Bethesda make and show how different approaches can lead to different types of gameplay experiences and how different level designs can favor one form of content scaling over another.

Article Scope: Note that this article does not address the issue of character leveling or character builds, or how a particular character build compares to enemy challenge, only how the world is delivered to the player in terms of his or her character level. As far as individual character builds go as it relates to enemy difficulty, this article assumes that player level = enemy level where, all other things being equal, a moderately experienced player will defeat an opponent of equal level roughly 50% of the time.

This article also does not discuss different types of level design (for example: linear vs. open world) except as it relates to content scaling. Look for future articles on these and other topics.

Before we can begin our discussion of level scaling, allow me to define a few terms.

Static Level Scaling

How difficulty scaling is handled varies by game and depends largely on the developer's objectives. In a completely linear game, in which the player always progresses through the same areas in the same order following a well-defined narrative, developers frequently employ a completely static approach: the same enemies are always encountered in the same locations, equipped with the same weapons, and drop the same loot; 'health kits', 'power-ups' and other rewards are also typically found in the same locations or acquired by following the same series of steps.

While this approach may affect the replayability of the game for some people (a subject I will return to later), developers using this approach can rest assured that, with proper testing, the player is always going to be faced with an appropriate challenge and receive a commensurate reward. Theoretically, this is the best way to design a game so long as the game is linear and designed for a single playthrough: every player has the same experience and all of the elements of the game can be finely tuned to maximize dramatic effect and game balance. This is the 'technique' that novel and film writing employ and essentially boils down to reducing challenge and reward to plot elements.

While static leveling may be employed in any game, this approach is especially useful for games which depend heavily on a linear narrative in which the opponents and the objects obtained by defeating them play a large role in furthering the development of the plot. For example, many games utilize the acquisition of a collection of powerful objects (or fragments of a single powerful object) as a motivating force driving the plot and have each object or fragment guarded by a powerful 'boss' enemy or appropriately scaled challenge. While the plot itself does not necessitate a linear experience (vis the Staff of Chaos in Arena), it does lend itself to one. (Skyrim uses a similar plot device in the form of dragon shouts 'guarded' by dragons rather than material objects.) In the context of a linear narrative, object and enemy scaling doesn't really exist as a separate element apart from gameplay balance, plot, and narrative.

The static approach to level design was very popular with classic arcade games and remains the most popular and appropriate choice for many games today. Static scaling may also be appealing to players who like to approach the game as a kind of test or puzzle in which bragging rights are earned for playing a perfect game (typified, for example, in speed runs). Static scaling provides the greatest amount of control over gameplay balance with the smallest expenditure in developer resources and will always be a popular choice in game design.

Random Level Scaling

At the opposite end of the spectrum is random level scaling, in which the enemies and rewards are not scaled to player ability but determined in a completely arbitrary and random fashion by using algorithms. I don't know if any game utilizes this approach in a pure form, though certain mods for Oblivion, for example, advocate a kind of scaling similar to this. In a completely linear game, in which the player is always forced to progress through the same areas (levels) in the same order, random level scaling is not a good option: no two players will have the same experience, and while one player may, through chance, experience an entertaining and well-balanced game, the vast majority are going to experience a game which is either too easy or too hard. In this case, we can see a direct relationship between level scaling and level design in which a linear level design supports a static difficulty scaling better than a random difficulty scaling. Open world games, however, are another matter.

In an open world game, in which the player is free to explore any area of the map at any time, a serious case for random level scaling could be made. After all, our experience of the world is often random, or at least appears to be so, and in an open environment, a random scaling mechanic might add a feeling of realism, danger and uncertainty to a game; these are certainly elements a player is looking for when sitting down to play an action/adventure game. Random level scaling lends itself to surprising turns of event and really is one of the foundations of emergent game play. It is the random element which affords the player the opportunity to witness events like a spontaneous battle between a giant and a dragon, or the sudden appearance of a coven of witches hunting mudcrabs in a stream in the middle of the night. While these events could be scripted, the knowledge that they are not lends a magic to the experience that is lacking in a statically designed game and is one of the chief attractions of playing a game like Skyrim or Oblivion.

There is always the chance, of course, that random level scaling is going to produce wildly different experiences for different players, though the effects are significantly mitigated in an open world environment. In a linear game, where the player is not able to change course, random scaling may create a situation in which a player may encounter an opponent which is simply too difficult to defeat, thus effectively ending the game on a note of frustration. In an open environment, the player can always choose to leave the area and perhaps return at a later time when they are more powerful, or when less difficult opponents have spawned. Over the course of exploring a large map with a large number of enemies, most players experiences will level out as the law of averages levels the playing field. Still, there are always going to be players at one end of the bell curve or the other who, owing to nothing but chance, experience a game which is either too unforgiving and unrewarding, or too easy and generous. Even in a completely open environment then, we can see that a purely random system of scaling is less than ideal for developers who want all players to enjoy their experience roughly equally.

Dynamic Level Scaling

In order to offset the arbitrary and unpredictable nature of random level scaling without sacrificing the emergent nature of gameplay not afforded by a static system, developers turn to a mechanic which we'll refer to as dynamic level scaling.

Dynamic level scaling is a more or less heavily modified form of random level scaling which employs static elements to mitigate the unpredictable effects of chance. As various elements may be chosen and these elements may be combined in innumerable ways, there is no clear-cut definition of dynamic scaling. At one end of the spectrum, you might have an otherwise linear game that produces random loot drops from opponents. At the other end of the spectrum, you might have an otherwise random game that employs level caps, where everything is randomly generated but enemies and loot never fall below or above a certain predetermined threshold relative to the player.

Dynamic level scaling generally revolves around one of two pivots: player-centric scaling, where the rewards and dangers are scaled relative to the player's level regardless of his or her location in the game world, or place-centric scaling, where the rewards and dangers are scaled relative to some location in the game world regardless of the player's level. Place-centric and player-centric scaling only make sense in the context of open world games since, by definition, linear games scale challenge and reward to both player and location simultaneously.

While some games may use player-centric or place-centric scaling exclusively, most open world RPGs use some combination of pivots to achieve a good mix between player ability and world plausibility.

Player-Centric Leveling

Player-centric leveling adjusts the difficulty of the opponents and rewards to the level of the player regardless of his or her location in the game world.

Player-centric leveling is driven primarily by the need to maintain balance in a game and to make it challenging for everyone without the game becoming too hard or too easy. By ensuring that the challenge never exceeds the player's ability to handle it, and that the reward never unbalances the game in favor of the player, player-centric leveling hopes to eliminate the frustrations of being unfairly matched or of being too 'uber'. One of the chief advantages of player-centric leveling is that this mechanic allows the developers to maintain a game's challenge indefinitely: by scaling the challenge and the rewards to the player, the player is guaranteed to be challenged and rewarded no matter what level they obtain.

The first disadvantage of player-centric leveling is that it removes the ability to control the level of challenge from the player. When enemies are directly scaled to the player's level, the player rarely finds weaker enemies if they are looking for something a little more relaxing, or tougher enemies if they are looking for something a little more challenging. The difficulty presented by the game is homogenized in the interest of streaming a particular difficulty level. This homogenization can be not only frustrating, but stultifying as it reduces one aspect of gameplay variety.

The second disadvantage is that it robs players of the sense of progression, a key component of RPGs. Although they may hit harder, and their armor may absorb more damage, because the enemies are always scaled to the player, the increase becomes invisible: enemies take more damage to kill and deal more damage themselves, thus the experience of fighting a bandit on level one is often indistinguishable from the experience of fighting a lich on level thirty.

The other disadvantage to player-centric leveling is that it produces unusual inconsistencies in the game world. When all of the enemies in an area suddenly become much more powerful, or rare items much more plentiful, the internal logic and coherency of the game world comes into question and immersion suffers. Oblivion is an example of a game which used player-centric scaling intensively; and, as many players are aware, it was also the single biggest complaint against the game.

Place-Centric Leveling

Place-centric leveling adjusts the difficulty of the opponents and rewards to an arbitrarily designated level assigned to a location in the game world, rather than the level of the player. Typically, locations which are further from civilization, or dungeon levels that are 'deeper', are considered more dangerous and produce more difficult opponents and provide more compelling rewards. The first advantage of place-centric scaling is that it allows the player to control the amount of challenge they want to experience: if they want something easy, they can stay close to home, if they want something more challenging, they can explore further afield.

The second advantage is that it validates the player's sense of progression. If a player wants to experience just how much more powerful they are now than they were at the start of the game, all they have to do is return to the areas they started in, or fight the enemies they fought at lower levels. (Of course, in order for this to work, the game has to respawn these areas, which is a separate gameplay issue.)

The third advantage to place-centric scaling is that it appeals to players' intuitions about the world: monsters and treasures are always appropriately scaled to the game world, so sudden spikes in enemy difficulty or an influx of wealth don't threaten the internal coherence of the world and immersion is preserved.

The chief disadvantage of place-centric level scaling is that, at some point, the game must cease to be challenging. Sooner or later, the player is going to be higher level than the most powerful enemy in the game and possess all of the best items. At this point, the game ceases to be rewarding. Developers typically try to avoid this issue by placing a level cap on the player roughly equal to the maximum challenge presented by the game, but this mechanic introduces its own complaints and effectively changes nothing: at some point, the game is simply no longer worth playing without starting over again from scratch.

Dynamic Leveling and RPGs

In traditional fantasy pen and paper (PnP) RPGs, there is a very close relationship between player level, enemy level, loot level, and location, much as there is in a linear game.

Generally speaking, as players increase in level, they travel to more exotic locations, encounter stronger enemies, and discover more valuable loot. This characteristic can be defined as both player-centric, where obstacles and rewards are adjusted relative to the player, and place-centric, where obstacles and rewards are adjusted relative to the location. As, typically, the player will only generally adventure in areas appropriate for his or her level (as determined by the game master), there is no effective difference between a place-centric and player-centric approach to leveling; or, rather, this degree of differentiation does not yet exist in PnP RPGs. Linear games use the same approach, and, while linear games and PnP RPGs are significantly different in other regards, in regards to leveling they work more or less the same way. (Yes, I'm sure you can think of exceptions to this rule.)

Traditional PnP RPGs achieve their dynamism by using two related techniques: random encounters/loot rolls and die rolls. Random encounters and loot rolls add variability to the player's experience, and are generally scaled to the player/location. Die rolls introduce small variability within the enemy/reward itself, providing an element of danger and uncertainty to encounters which are otherwise more or less directly scaled. (In real-time RPGs, combat die rolls are sometimes replaced by 'twitch' mechanics that rely on the player's ability to target opponents and dodge attacks instead of relying on the character's stats. These kinds of RPGs are relatively rare, though Bethesda is fond of a hybrid real-time/stat-based combat.)

Dynamic Leveling and MMOs

The undifferentiated player/place-centric approach to scaling which is native to linear narratives and PnP RPGs is consciously and explicitly applied to many MMOs. In many MMOs, many locations are 'zoned', or restricted to players below a certain level, thus enforcing the player/place centric identity in level scaling.

Restricting access to certain zones based on an external game mechanic like player level (as opposed to an organic mechanic like having opponents which are too difficult for the player to defeat) results in a less open world experience which might best be described as a staged world (as opposed to an open world or linear world). In a staged world, successively harder locations are unlocked by leveling the player. Staged worlds generally allow the player free access between worlds that have previously been unlocked and are rarely static in design (aside from the staging of the worlds themselves, of course). Within the worlds that are available, players will generally encounter dynamic leveling, where monsters and loot are scaled relatively to the player's level but are not statically placed.

Staged worlds both are and are not player and place-centric. Because the locations available to the player are themselves scaled to the player, there is no effective difference between the player's level and the level of the geographic region of the world. Some variability is introduced by allowing players to return to easier locations (thus preserving the sense of progression) but by limiting the player's ability to take on greater hardships and earn potentially greater rewards it removes some of the control from the player. This can be seen as a sort of hybrid place/player-centric mechanic.

Dynamic Leveling and Single-Player CRPGs

Developers of single-player CRPGs, of course, have a much broader range of choices. Single-player CRPGs run the entire gamut of designs: everything from randomly generated levels with random enemies and loot all the way up to strictly linear affairs where the range of player choices is restricted to a tiny subset of possibilities, such as which skill tree to develop or what gear to equip. Open world CRPGs like Skyrim, which allow the player to roam freely around the game world, generally enforce level scaling through either player-centric scaling, place-centric scaling, or some combination of the two.

In Oblivion, most level scaling was player-centric: enemies and locations would become progressively harder as the player progressed regardless of his or her location in the game world. This produced situations where bandits, who would rob you for a bit of gold, were already wearing full suits of valuable armor and weilding extraordinary weapons that would have allowed them to retire in splendor from a life of petty crime. Players also often complained that they felt robbed of their sense of progression and that they never really felt like a hero. If, after twenty levels, the bandits trolling the bridge on the Red Ring road were every bit as powerful as the player, it made them question the value of their efforts. (Ironically, Oblivion's player-centric level design appeared to be designed in response to complaints about Morrorwind's more place-centric design where player's often complained that the game became too easy at higher levels.)

The challenge for Bethesda, in designing Oblivion, which is an open world game, was to provide a challenge for players regardless of level and location. As players could go anywhere at any time, they could not count on providing the player with an appropriate challenge and reward based on where they happened to be in the world. Player-centric level scaling was the obvious design choice, but as we've seen, not the best one.

Encounter Zones

In Fallout 3, Bethesda addressed this issue by introducing the concept of encounter zones. The encounter zone concept works like this: when a player first enters a location, such as a dungeon, the enemies and rewards are player-centric, scaled to the player's level. Once the level of the enemies and loot has been set for a location, however, that location is locked down: it becomes place-centric, and the level of future loot and enemy spawns becomes more or less static. This mechanic elegantly resolves the issue between player-centric and place-centric scaling by adopting strategies from both mechanics.

The encounter zone mechanic by itself isn't perfect, however. While it resolves certain issues, it leaves other elements unaddressed.

For example, it doesn't allow the player to challenge themselves by entering areas considered 'above' their level. Since the level of an area isn't set until the player enters it, the game has no way of offering this experience through encounter zones alone. In this way, it is similar to staged level scaling where certain areas are off limits; however, in this case, these zones are not prohibited, they simply don't exist until the player reaches the appropriate level. Bethesda addressed this issue by providing minimum levels to encounter zones, though these minimums were generally fairly low. Placing a minimum level on an encounter zone effectively introduces an element of place-centric design into a player-centered design, forming an elegant compromise.

One minor complaint that players have with encounter zones is that it introduces inconsistencies into the game world. Suddenly, areas that once seemed challenging seem out of place by being locked in at a lower level. Depending on the path the player takes, one area may become locked to a low level, while all of the surrounding areas that the player neglected to explore the first time through may suddenly become very high level. This is noticeable when the player focuses on the main quest, for example, early on in the game and only later explores other areas. Suddenly, the locations which served as dramatic set pieces in the main quest take on the pallor of pathetic relics that remind one only of one's humble origins.

It is important to note that static level scaling in an open world avoids both of these issues: because regions of a much higher level exist from the very start of the game, players always have the option to challenge themselves in pursuit of a great reward. This option was available, for example, in Morrowind. Additionally, because the difficulty of the zones is set by the developers, they generally follow a natural progression, becoming progressively more difficult the further from civilization one goes.

Although the encounter zone mechanic goes a long way toward improving gameplay balance in an open world, one significant charge that can still be leveled at them is the lack of uniqueness or interest provided by these zones. (A charge which can be equally leveled at any dynamic system, of course.) While encounter zones may be a step in the right direction, then, they are clearly not the whole story.

Unique Items and Encounters and Mixed Leveling

One problem that encounter zones does not solve is how to handle unique items and encounters. In a statically designed game, there is no such thing as a unique item or encounter: everything is quite consciously and specifically placed by the designer, so it can only loosely be described as being 'unique'. The same steps will always lead to its encounter or acquisition. In a dynamically generated game, however, whether or not unique items and encounters exist and how they are handled can have a significant impact on how the player views the game.

A game that completely lacks unique items and encounters frequently feels devoid of depth and history. Much of the flavor and character of a game world, in fact, is defined by the unique items and characters that the player encounters. These are the experiences that are 'set apart' and stand out by virtue of their unusual history or purpose.

Developers have typically followed a couple of different approaches when integrating unique content: they either create some areas statically, with hand-placed items and enemies or they add non-recurring items and encounters to leveled lists. Typically, developers opt for the former because it allows them to control how and when the player experiences special content and most if not all of these unique items are typically quest (if not main quest) related. Using non-recurring items in leveled lists is much trickier to get right and is generally reserved for interesting but non-essential items and encounters.

Most open world RPGs use some combination of dynamic scaling and statically placed objects and encounters which could be described as mixed level scaling. In a mixed level scaling system, many objects and encounters will be scaled to either the player or the location, but some objects and encounters will stand out as being relatively unique, but not necessarily well-scaled to the player. If a game relies heavily on player-centric scaling (as Oblivion did) then it might best be described as player-centric mixed scaling. By contrast, a game like Morrowind, which relied more heavily on static item placement, might be better described as place-centric mixed scaling.

Randomly Generated Items: Some developers simulate unique items by randomly generating items from combinations of item characteristics: if there are a large number of different characteristics, and some of them are very uncommon, it is possible that the players will only rarely discover an item possessing that particular combination. For example, a pair of gauntlets that grant the wearer additional strength, make it easier to craft items, and provide protection from fire-based attacks. This is not typically a replacement for placed unique items, but it can serve as a good addition to a game's repertoire.

Content Scaling in Skyrim

Skyrim appears to be an evolution of all of these foregoing strategies: it uses both dynamic and static items and encounters, uses encounter zones to simulate place-centric scaling, and scales other elements, including quest rewards, to the player.

All in all, Skyrim does a much better job of scaling opponents and loot to the player than Oblivion did while retaining some semblance of logic and continuity in the game world. The 'off the beaten path' locations, some of which appear to be zoned to a fairly high level, do much to ameliorate the complaints of many players about the homogenous nature of encounters in Oblivion without introducing linearity or restricting the ultimate challenge of the game. These locations which are much more powerful than the player from the very beginning of the game, provide players who like a good challenge with the option of testing themselves in the pursuit of greater rewards.

Likewise, Skyrim does a better job of preserving lower level mobs by providing enemies that don't scale, or who only scale a little, thus better securing the player's sense of progression. Skyrim represents a very sophisticated merger between static and dynamic content, and player and place-centric scaling, and brings about a more or less steady balance between these divergent elements, a feat for which Bethesda should be justly recognized.

In spite of this, there are still some small issues with Skyrim's leveling mechanic. The difficulty of quest locations is still largely player-centric, for example, to allow players to complete the main quest early on, but as a consequence of this, dragons and certain other opponents may seem rather underpowered in some circumstances. Additionally, because quest rewards are scaled to the player, it is sometimes advisable to delay certain quests until later on if one wants to maximize the benefit that they offer. If these are the worst charges that can be laid against level scaling in Skyrim, however, gamers have little to complain about. (Indeed, the key complaint about Skyrim seems to be about the way that player's level and how that level is balanced to enemy difficulty, as opposed to the way that that leveled content is delivered. An excellent discussion for a future article.)

Conclusion

Content scaling has always been a core design challenge for open world RPGs. The need to balance gameplay against player freedom, to simulate a world that behaves rationally, providing reasonable challenges and rewards in a way that makes sense intuitively to players without becoming a lifeless and homogenous mess is no simple design feat.

This article has looked briefly at a few of the options available for designing scaled content in the hope of illuminating some of these issues for players who may take issue with the decisions made by developers. Hopefully, it may also serve as a springboard for discussion and analysis of the techniques used in these and other games to help developers and gamers better understand the issues and opportunities that exist. At a minimum, I hope you found this introduction of a core game design topic interesting, reasonable and immersive without being too challenging or unrewarding.

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Last updated November 27, 2011

© 2009-2011 Dave Finch

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