[Experienced MMO designer Brian "Psychochild" Green pulls at the MMO trinity -- Tank/Healer/DPS -- to examine whether or not this pillar of combat design can be pulled apart, modified, or even changed fundamentally.]

Designers, like many people, tend to fall into habits and patterns. Our games fit into specific genres, so they tend to be similar to other games in that same genre. Best practice is to borrow systems that work well in other games. However, sometimes a system gets enshrined into the conventional wisdom; once that happens, we rarely turn a critical eye to these systems and see if they are really meeting the design requirements. MMORPGs experience this type of "inherited design" for many gameplay systems.

The Trinity of Core Roles

One common design in MMORPGs is the "holy trinity" of class roles: Tank, Healer, and DPS (or damage dealers). As most games are about combat, these roles are about how damage is handled: Tanks can mitigate incoming damage from enemies, healers restore damage done from enemies, and DPS classes do damage to enemies.

Characters often require specialization: a superb healing class may not be able to do good damage without a significant change that hurts healing ability, or they will often not want to do damage because they need to save their resources for healing others. This trinity of classes forms the basis for most group-based encounters in a game.

There are other roles of characters possible in these types of games. For example, "crowd control" (CC) classes can temporarily take enemies out of the combat, and "buffer" classes can use abilities that enhance the abilities of other classes.

These additional roles are often combined in a class with a primary role: a healing class might get good buffs, a DPS character may be able to control extra enemies, etc. These other roles can also be taken care of by the core roles: a secondary tank can keep multiple enemies occupied if crowd control is not available, for example.

Finally, the DPS role sometimes has specialized categories: melee, ranged, single-target, area of effect (AoE), etc.

Our design goal for this article is to look at alternatives to the trinity design. First, we must understand the details of the trinity design, what design goals it accomplishes, and what type of design could replace it. For this discussion, we'll make a few assumptions:

For this article, design is the only focus. Technical limitations tend to be specific to each game and therefore of limited use in a discussion. Other vital issues, such as community management of player expectations, are also beyond the scope of the article.

The History of Classes and the Trinity

It is useful to look at the history of character classes in RPGs to trace the origin of the trinity design. Classes were part of the first well-known RPG, Dungeons & Dragons (D&D). Each character had a class that determined his or her abilities: equipment that can be used, hit points, magical ability, etc.

Each class was based on a fantasy archetype, but without explicit roles; there was no rule that a Fighter could only absorb damage (be a Tank) and not be an awesome machine of death (be DPS). Each class had signature abilities, but statistics and options allowed characters to fill a variety of roles despite their class.

Over time, certain patterns of gameplay emerged: for example, the physically fragile low level wizard might prefer to be protected by the heavily armored fighter instead of rushing forward to engage enemies on the front line.

The MMORPG EverQuest (EQ) had the concept of classes and started the focus on the trinity of core classes. Inspired by a text MUD that was based on a D&D game setting, EQ had a class design that borrowed heavily from the older D&D system.

The core trinity of roles rose to prominence in high end raiding: a character tanked the boss, healers had to keep the tank alive, and other players hurt the boss without drawing too much attention to themselves. Each class had a single role it did well: Warriors were always Tanks, Clerics were always Healers, etc.

World of Warcraft (WoW) borrowed from EQ's class design and refined it. It added different talent trees that allowed a single class to specialize. WoW's expansions allowed some classes to fill multiple roles through talents; a Druid is able to become a Tank, a melee DPS, a ranged DPS, or a Healer based on equipment and talents chosen. A single character is usually expected to only fill a single role in one encounter.

Paper RPGs have been developing during the years as well. The fourth edition of D&D comes full circle, and the venerable paper RPG has been inspired by MMORPGs. In the latest edition, classes have gotten explicit roles as part of the class description, although it doesn't quite use the same roles as the trinity.

Other systems have gone away from classes and roles; for example, GURPS and the White Wolf's World of Darkness have had more flexible character development systems that rely more on lists of skills that any character can take rather than on strict classes and roles.

Design Analysis of the Trinity

Before replacing the trinity of core classes as a design, a designer's analysis is in order. What is being replaced? What parts should be retained? What parts cause problems for other parts of the design?

The Trinity in Practice

The important part of a design is how the players interact with the system. How does this design work in a live game?

One role is much more popular than the others: DPS. Most quests and experience systems only offer rewards if you defeat an enemy in combat, not necessarily if you're good at mitigating or healing damage; therefore, characters that can defeat enemies faster are easier to advance.

Offensive ability is often prized in direct competition, such as PvP combat, where the person who can do the most damage in the shortest amount of time can win a surprise encounter. These factors influence many players to favor DPS classes.

Healing and tanking, on the other hand, are more specialized roles that generally work best in a group situation. People who prefer these roles will have a poorer experience if most other players prefer solo content. Most players who excel at the group-focused roles will often need to find regular groups to advance, and this means there will be few of these roles available to other characters for pick-up groups or recruiting into guilds.

It's easiest to judge the performance of a character in the DPS role. Savvy players use programs to analyze combat output and figure out relative performance. It's easier to see the result of a small change made to the character.

Judging improvements of a Tank or Healer role is more difficult and extreme because their performance affects the whole group. Performance isn't a matter of degrees for these other roles, but a binary situation; if the Tank or Healer dies in a small group there may not be another character able to take over the tank role and continue the encounter.

Advantages of the Trinity

The reason the trinity design is so popular can be summed up in a single reason: it works. And it works in many different games. But, why does it work so well from a designer's point of view?

The system is well-tested and any problems are well-known. The system is found in many games, so development is faster and easier than trying to come up with an original system. Any flaws in the system will also have other groups working to fix those problems as well.

It is easier to design encounters. The composition of a typical group can be anticipated to some degree, and it is easier to design the encounter with this theoretical party in mind. It is also easier to design challenges to the party; for example, having an encounter where two different opponents must be occupied by a tank, requiring an off-tank or a single tank to keep both occupied.

Players generally understand and identify roles easier. A majority of players will understand their roles in combat easier having played similar games. The roles are very simple to explain briefly, making writing a tutorial or manual easier. Players can represent their roles to other players easily; the phrase "I'm tank spec" gives a lot of information to another player in few words. Players still need to identify subtleties based on other cues: a Cleric healer is going to have a different healer role than a Bard who has a few emergency healing spells.

Playing a different role increases replayability. If a player tires of their main character, they can try out a different role for a change of pace. While some players may identify closely with a single role, many players will want to explore. Playing with a group as a Tank is different than experiencing it as a DPS, even if the player is going through exactly the same content.

Disadvantages of the Trinity

Unfortunately, there are also some problems with the trinity design that can hinder a game. We want to avoid these problems in any new system we design.

Groups seem restricted to limited composition. If every encounter is balanced with the assumption of having a specific group composition, then the players may feel restricted to only having an "optimal" group. Some players may be excluded because their class isn't in favor, or because there are too many others able to fulfill that role. Limited group options can also cause frustration if players cannot get the "necessary" roles to participate; a group will fall apart without a specialized role like the Tank or Healer.

Roles don't translate well to other forms of gameplay. If your game focuses on group content, then the trinity of core classes works well. However, few games focus entirely on a single type of gameplay. Solo players may find some roles harder to play outside of a group. In PvP, the weaknesses of some roles may be exploited freely; for example, a Tank's aggro/hate management abilities mean little when fighting against other players.

Limited roles restrict player choice. If priests are restricted to the Healer role, then a player cannot create a holy character who smites evil as allowed in other games. Hybrid classes with multiple roles are always difficult to implement properly -- players who play a class with a single role will be upset if another class with multiple roles can do their role just as well or better. But, a hybrid character that seems weaker in a role may not be perceived as powerful enough and people playing that character may feel left out.

Systems tend toward complexity, causing confusion. As a game develops, the systems will become more complex. A class that focused on a single role may get abilities that expand into other roles. For example, at the launch of World of Warcraft a warrior was primarily expected to be a Tank because they were the best and other warrior specializations were ignored as inferior. Many years later, a warrior can fill a DPS role and other classes can handle the tanking role just as easily.

The trinity does not make sense in some settings. Why would a game set in space with ships have a Tank or Healer role for the ships? What about a realistic modern infantry warfare? You can make it work, but this can hurt the willing suspension of disbelief. The trinity of core classes does not make sense in many settings outside of fantasy.

Alternatives to the Trinity Design

Let's take a closer look at what type of system could replace the trinity design.

Design Goals

The first step is to decide what our design should accomplish. As a guideline, we should look at the advantages of the trinity design and identify which of them are necessary to keep in an alternative design. My preferences would be:

A diversity of character types. Players want to have some unique features, so we don't want there to be a single "proper" type of character that a player has to use to compete.

Ease of balancing for developers. Balance issues can upset players in a game, so we would like a system that is easy to balance from a developer's point of view. Balance issues can also limit the diversity of character types from the previous goal.

Solid direction for player advancement. Starting a new character should not be a confusing process for the player. Players should understand the paths available for advancing their character early in the character's life.

Ease of identification of other characters. Players should be able to easily identify how a character could be used in an encounter. We want them to understand how to build a character and how that character will fit in with the other members of a group.

Possible Solutions

Skill-based systems, a common alternative to a class-based system, allow more character customization. A player can choose what roles they can fill and how strong those roles are by their skill choices. A skill-based system offers the player a lot of opportunity to develop and customize their own character.

Unfortunately, skill-based systems also have some well-known problems. The first is that they can be hard to balance, especially for inexperienced designers. This problem is exacerbated by the fact that players will take the most powerful set of skills available, leading to a lot of "flavor of the month" setups.

Because of this problem, characters are not diverse, despite a system that should allow for a wide variety of abilities. A skill-based system with some refinements, such as opposition skills that cannot be taken together, could solve some of these well-known issues.

A hybrid system mixing a class-based and a skill-based system could also allow for more flexibility in the roles characters could fill. This type of system would put skills into different groups and allow players to select a limited number of groups of skills for their character. The combination of different groups of skills leads to a wider variety of characters.

In single-player games, Titan Quest allowed the character to pick two groups of skills out of eight possibilities. The MMO Meridian 59's design allowed players to select abilities from seven different schools of abilities based on the gods of the setting. Since skills are presented in groups, it encourages more variety without players simply cherry-picking the most favorable skills.

Characters able to fill multiple roles is another option. A single character could fill the DPS or Tank role, for example, based on choices the player makes. Characters may be restricted in some way, such as requiring a cost to switch roles, specialized equipment for each role, or limiting the character to a specific role for a period of time.

An example is the Runekeeper class in The Lord of the Rings Online, where the type of abilities used (damaging or healing) gives the character an "attunement" that enhances those types of abilities and restricts the use of opposing abilities; thus the Runekeeper can be either DPS or a Healer in a battle depending on what abilities have already been used in the combat. While this doesn't eschew the trinity design completely, it allows for some flexibility.

Of course, not every solution has to be an incremental change from existing options. If the project allows more freedom than allowed here, a radical re-design of core mechanics is possible. The design could change the nature of how combat works in a game and thus eliminate the concept of the trinity of core roles entirely.

Such a system might do away with the concept of a high number of hit points so that combat isn't just about reducing an enemy's health. The goal of combat would go beyond causing or preventing as much damage. This system might focus more on disabling the opponent, or building opportunities to get a decisive blow in. However, this design would take a lot more work to design than the other incremental approaches suggested.

An Example

Allow me to present a concept for a fantasy combat-focused MMO as a model to discuss.

Inspiration

Let's take another look at the great grandfather of class-based fantasy games, Dungeons & Dragons. Early D&D had wide selection of classes with different abilities. Different classes had different specialties and different focuses in combat abilities.

Classes that wore heavy armor, such as Fighter classes and Clerics, could survive on the front lines of battle because they could avoid hits easier. Fighter classes could also do tremendous damage with heavy weapons against most opponents.

Rogues preferred more subtlety and stealth, with their abilities focused on sneaking past enemies and striking them while vulnerable. A Rogue class might be able to stand toe-to-toe with an enemy for a while, but that was a risky proposition.

Magic Users and other caster classes were not warriors, but they could bring power attack spells and tremendous utility spells to bear in the game; however, they were often limited in how much they could do in a single encounter.

Even though each class had their specialties, few were exclusive to that class. A Rogue with magical equipment might be as well protected as a Fighter in plate mail. That Fighter may obtain an enchanted weapon and thus be able to do significant damage to match a Rogue class over time.

Party composition was also not as strict. For example, being without a Fighter class in heavy plate armor (a Tank in the trinity design) wasn't always a disadvantage; in fact, the party could use stealth easier without members stomping around in a loud metal suit of armor. Magic items such healing potions, magic wands, spells scrolls, protective items, and so forth could also partially replace a missing role.

D&D had four archetypes -- Fighter, Cleric, Rogue, and Magic User -- but there were many different classes. Fighters, Paladins, and Cavaliers are related but play quite differently. Clerics and Druids cast divine magic, but their differing equipment and ways of using divine power make them distinct. Rogues and Bards had similar skills, but they had different specialties to bring to a group so having one of each rarely felt redundant.

The Proposal

Given the history we find in D&D, we aren't forced to abandon familiar combat systems in order to replace the trinity class design; however, we do need to change what we expect from individual characters. The two main concepts for guiding a different design are to eliminate specialized roles and allow the use of tactical options in combat.

Eliminating specialized roles means that we do away with boxing a class into a single role. Without Tanks, each class would have features that would help them participate in and survive many different encounters like heavy armor, strong avoidance, or some class or magical abilities that allow them to disengage from direct combat.

Without specialized DPS, all classes should be able to do damage in order to defeat enemies. Some classes might be specialize in damage type like area of effect (AoE) damage, others might be able to exploit enemy weaknesses, and some might just be good at swinging a sharpened bit of metal in the right direction at a rapid rate.

This design isn't just about having each class able to fill any trinity role. MMO combat would feel more dynamic in this system. Every player would have to react to combat events and defend against attacks. Some characters might be able to protect others, but it wouldn't always be the heavily armored character trying to draw a majority of the enemy's attention. Healing would be more of an emergency thing done at a cost in combat to help a character that has not been defending well.

Obviously good class design is important in order to provide tradeoffs between the classes. A heavily armored fighter with a big sword might not be able to defend against magic attacks, whereas the magic slinger might fall prey to sneak attacks if not paying attention. Each class would still have strengths, weaknesses, and individual flavor, but they wouldn't fall into the precisely defined roles that the trinity design encourages.

This doesn't necessarily eliminate the trinity of core roles from the game, however. A player could decide to focus on being able to take repeated, punishing hits while protecting other players and therefore fulfill a Tank role. However, eliminating explicit roles means that players are not forced into a specific role through class choices or game design requirements.

Use of tactical options in combat, like in paper D&D games, requires a different paradigm for gameplay than found in current MMOs. Maneuvering and physically blocking movement of enemies becomes much more important than it is in current games if the group needs to protect a wounded member who can't just be healed by the specialized healer standing in the back

Party members might be encouraged to use terrain and location as an important component of strategy. Ranged attacks could become more interesting if the players can make their characters use cover, or if they have to worry about firing projectiles into a melee involving group members. Combat could be a lot more dynamic than standing at optimal range and using special maneuvers.

Unfortunately, the biggest drawback of allowing tactical options in combat is that it will run into technical limitations given internet latency and cheaters. The phrase "using terrain" in MMOs usually refers to the exploit of harming NPC opponents while putting them in a position to be unable to harm the character. As the design is fleshed out, more of these issues will come to light and it may require adjusting some combat mechanics.

Meeting The Design Goals

Let's review our design goals listed previously and how this new proposal satisfies them.

A diversity of character types. The character types are only limited by class design. As pointed out, the old D&D games had a wide variety of classes with different flavors and each archetype had several subtypes. A game using this proposal may see an increase in character types since they don't have to fit within a small selection of specific roles. If the gameplay doesn't punish some types of combat (e.g., enemies with specific damage immunity), different classes should be equally viable in the game.

Ease of balancing for developers. This is the difficult one. Increasing strategic options in combat will be hard to implement and to balance properly. It would be easy to give a class an overwhelming power, such as restricting enemy movement, which makes the class feel very powerful and therefore "necessary" for group composition. To be fair, this is going to be a problem with most original designs.

Solid direction for player advancement. This is possible with good class design. Players won't be stuck trying to solo with group-focused roles if they can handle most of the elements of combat within their limits. A player should be able to build their character to take more advantage of the class features they truly enjoy using.

Ease of identification of other characters. Once again, a class system gives a good shorthand for identifying other characters. This becomes less of an issue if the classes are balanced well; without specialized roles we won't have to worry about finding someone to fill a specific role to "complete" the party.

Conclusion

Designers often find it easier to simply copy mechanics that seem to work without really analyzing them. The trinity of core classes works well in many games, but the design can be limiting if it is copied without critical analysis. By taking a look at the design principles, we can identify the good parts and refine those into a better system.

Not only does this give a game a different and potentially better gameplay experience, it can also be a unique selling point to allow your game to stand out in a crowd. A top designer must take time to really analyze a game system to understand why it works in another game and how it can improve their own designs.