Wednesday, October 28, 2009

Mechanic Assessment: Use-based Skill Gain

(I made a more recent post which basically replaces this one while doing a much more thorough analysis. Please read it instead of or in addition to this one.)

From my experience with use-based skill gain systems in Oblivion, Morrowind, and Darkfall, I’ve noticed that such systems are inferior. They should be avoided in favor of other approaches to skill-based advancement (as in Fallen Earth) and class/skill hybrid systems (like the one in Final Fantasy Tactics).

First, three gamist reasons why use-based skill gain is an inferior character advancement system:

The character can only be rewarded for a much narrower set of tasks. And that set of tasks is doing whatever action the player wants to level. It’s not clear how quest (or whatever kind of achievement system you want) rewards can fit into this framework. Use-based skill gain cuts out an important part of the incentive structure. In an RPG like Dungeons and Dragons, Dogs in the Vineyard, or Mousegard, combat isn’t an end, it’s a means towards surviving a precarious scenario. There are other means, such as parley, avoidance, and escape that serve that purpose just as well. With use-based skill gain, it becomes difficult to reward the player character for accomplishing anything except easily quantifiable combat and crafting tasks. This leads to gameplay focusing on direct combat and crafting, which narrows significantly the effective and beneficial conflict resolution methods.

Use-based skill gain leads to runaway positive feedback loops that restrict character growth and ability diversity. I kill using ability A so ability A becomes more powerful so I use ability A to kill stuff. This loop generates a second-order effect on skill growth. If you only have a few abilities that are strong enough to use against mobs that drop worthwhile loot, you’re going to use those abilities frequently leading to them becoming more effective and the farming being more efficient and worthwhile. In this way, characters are stuck using the same abilities because only certain abilities are day-to-day useful. But all the abilities are on a similar scale. The Illusion and Mysticism schools of magic were like this in Oblivion: they had some nifty effects, but they were largely composed of utility spells that you would never justifiably use enough to keep the skill level competitive with your melee skills or destruction magic.

Use-based skill gain encourages and rewards exploitation, macroing, and cheating. Some skills necessarily will be used less than others. By factors of hundreds. This forces designers to balance skill advancement against use. This problem cannot be solved. Designers need to measure skill-use frequencies and balance that frequency against how difficult advancement should be. But if a player wants to level a skill, he’s going to find ways to use it more than is reasonable, throwing these calculations off and leading to imbalance. If the player wants to level his buffing abilities, he is going to cast buff spells on everyone he sees if he’s nice, but more likely he’ll cast a buff on himself, then dispell it, and repeat those two actions until he has the desired skill level. Players will always seek to find safe ways to level skills, trivializing the advancement system—developers will always be behind in preventing this kind of behavior. Exploiting and macroing becomes the only way for an honest player to keep up. Darkfall’s EU server has fallen victim to this problem. Exploitation is always the most effective way of increasing skills and it breaks the balance of skill gain.

And one simulationist reason:

Use-based skill gain doesn’t make sense from an immersion/metaphor perspective either. People do not go out and put their life in direct danger to advance from novice to super-novice at using a sword. They spend years practicing with the weapon for several hours every day. The time spent practicing far outstrips that time spent in actual life-threatening struggle. When you’re engaged in combat where life is in the balance, the amount of skill you have when combat begins determines if you live or die. You’re focused on survival, not on dinging 34 on your sword skill. Certainly you will learn from direct combat, but not even a tenth the amount you learned from training since you were the age of 10.

Use-based skill gain should be avoided for primarily these four reasons. As a mechanic, I thought it was a great idea before I played games that implemented it. Now I don’t see a reason to go with use-based skill gain over a different skill-based advancement system, such as purchasing skill levels with XP or some other broader resource.


Brian 'Psychochild' Green said...

Having been saddled with a game that uses this as an advancement system, I will agree with you in general. A few quibbles, though, as always:

1. Not using use-based skill system doesn't eliminate the fact that players will simply use a few powerful skills. Most WoW characters use a small selection of skills in a rotation, for example. Not using a use-based system does allow players to switch to using newly buffed skills easily if balance does change, however.

2. People still exploit, macro, and cheat in other systems. It's just that there isn't quite so direct a path to follow. I think the bigger issue here is competition more than the use-based system; if something will allow your character to have an edge over someone else, you'll do it.

3. Immersion/metaphor is not a consideration here. Even though battle doesn't necessarily give you huge improvement in your ability to swing a sword, neither does helping a town full of people to gather 10 flowers/pixie wings/mugs of beer. Let's just accept that a game world works with special rules that don't mirror the offline world and not drag out this tired excuse, 'K? If the game is going to have advancement, then whatever system exists is not going to mirror the offline world perfectly; playing through years of boring training to improve my skills doesn't sound like more fun. :P

evizaer said...

Notice that I'm saying that my points show that use-based skill gain is inferior to other systems, not that it is flat-out horrible. I'm not suggesting these problems don't exist in other systems, I'm pointing out that these problems are exacerbated by use-based skill gain mechanics.

1. That's a simpler balance problem to solve or lessen when you don't also have use-based progression to tweak as well.

2. Use-based skill gain is more exploitable and exploitation is more rewarded than in other systems.

3. The justifications I've seen for use-based skill gain have been immersionist in nature. Using something to improve it seems like a most intuitive idea, but it's not because the metaphor is off as I pointed out.

Experience points are a broad abstraction that you can reason about in a way that allows character growth be seem relatively sensible.

Brian 'Psychochild' Green said...

Notice that I'm saying that my points show that use-based skill gain is inferior to other systems, not that it is flat-out horrible.

Oh, you can say it's flat-out horrible. But, then so are most systems to advance in RPGs. However, I don't think pointing out flaws which are also in other systems demonstrates that this particular system is inferior.

That's a simpler balance problem to solve or lessen when you don't also have use-based progression to tweak as well.

As someone who has done both in an amateur and professional capacity, I disagree. No matter what advancement system you use you'll have to deal with it as part of the balancing act. Many designers probably feel more comfortable balancing class/level based games, though, so the perception is probably that it's "easier".

Use-based skill gain is more exploitable and exploitation is more rewarded than in other systems.

I still disagree. As I said, the path may be clearer and the exploits easier to do in use-based advancement as implemented in many games. However, an infinite experience exploit in WoW would be much more rewarded than macroing up your unarmed skill.

Experience points are a broad abstraction that you can reason about in a way that allows character growth be seem relatively sensible.

Sorry, you can't slam one system for not being immersive then make weak justifications for another. Experience points are just as hokey and contrived as use-based advancement, hit points, degrading equipment that can be repaired to full every time, fetch quests that reward character advancement, and a ton of other nonsense clich├ęs we see in these games. I could just as easily say use-based advancement is a "broad abstraction" for you putting your years of studying to use in practical situations; when you gain a point a lesson that was drilled into you finally clicks and your practical ability is improved for it. See? 110% bullshit in a bunch of pretty words.

As a designer you need to understand the difference between bad systems and the systems you are used to.

Longasc said...

Yep, this "skill gain based on use" system is flawed. But so far people seem to think there is only one alternative: XP point driven gain of "levels".

The usual levels vs skill based debate, basically.

But who needs use-based skill gain and levels? I think both can be mixed to some degree, where most characteristics of the usual level progression get lost. Guild Wars was already close to that:

It inherited the stat/attribute cap from Ultima Online, which also had a cap on skill level (100.0 was early on the max, and 700 pts could be assigned for all skills together at the maximum).

The cool idea is the ceiling, the cap on player stats/skills/item stats.

This is what kills most level based games that constantly add 10 levels. We already had single players kill raid bosses after the first expansion of a level-based progression game, World of Warcraft, The Burning Crusade and Onyxia might sound familiar, so I won't go into detail there.

Both level based and skill-use based systems have flaws. You did not mention level based systems at all, but it is still the only other major system used besides use-based skill gain.

You can also add LOTRO's kill deeds, you gain stat improving traits through killing 120 and later 240 Orcs in a certain area for example. But on the other hand the game has levels and XP mostly through quests based progression, too. There is also progression by using certain attack skills several hundred times, which basically asks me to execute them as much as possible, which is sometimes quite natural but sometimes awkward for special attacks.

Use-based skill gain is, despite the flaws nobody can deny, not as bad as you make it sound. Picking Flowers for Quest XP or collecting crap along the Nimrodel river is neither. So basically, LOTRO has both flawed systems in one package. I just realized that. xD

I am also a bit on the fence regarding Morrowind and Oblivion, as this advancement system is TOTAL BULLSHIT, but does not represent all use-based skill gain systems. I knew how to "play" the system to maximum efficiency in Morrowind, and if you do this, you really play in an awkward and unenjoyable way, but you maximize your stats. In short, in terms of Bethesda's Elder Scrolls games, I totally agree.

But in regards to other skill based games, Meridian included, the system is working quite well!

evizaer said...


I'm saying it's inferior. That means the exploits are easier and the balance is more difficult while not yielding anything that can't be accomplished without such intense difficulty in a hybrid system or a class-based system. You seem to think I'm saying that these problems don't exist in other systems. I'm not saying that at all. I'm saying that these problems are worse because they are easier to see and easier to exploit, while being harder to balance in use-based skill gain. You seem to be taking absolutist positions. I'm speaking in relative terms. (Now you're going to say that you still disagree and say that your experience trumps mine so I don't know what I'm talking about. Fine. Give me a couple ways use-based skill gain can be made good.)

I think I'll write a post that explores the effects of the mechanical difference between use-based and XP-based systems. It's a difference that deserves more examination than this brief flyover.

Brian 'Psychochild' Green said...

You seem to think I'm saying that these problems don't exist in other systems.

No, that's not what I think. I think you're saying, "Dogs are inferior as pets because they vicious teeth and a tail." I point out that cats also have frightening teeth and a tail. "Yes, but dog teeth are longer and the tail wags more."

It's not about saying that use-based systems are good, but accepting that level-based systems don't avoid the points you're talking about by default.

And just because you provoked me, I'll give you an example of a good use-based system: gaining hit points in Meridian 59. In order to gain hit points in M59 you have to fight opponents that have at least as many hit points as you do. Every time you kill an opponent (note: monster or player) you get a chance to gain a hit point if they meet the criteria. If you do not get a point, you will get a slightly increased chance next kill until you get a point.

You are rewarded for the same "narrow task" that level-based systems give most of their rewards for: combat. I think this is fair since hit points are only really useful in combat in the system.

There is no positive feedback loop because a character who gains hit points must increase their challenge in order to keep gaining hit points. Sticking with the same easy enemies will halt your advancement.

You cannot macro this any more than you can macro combat, which means that a level-based game is just as susceptible to this problem. You can't just murder a mule character since they lose hit points with every death; if they don't then the death does not count toward earning a hit point.

As I said before, I don't buy the immersion thing. But, if you want me to give you the pretty bullshit: a common explanation in other systems is that hit points are an abstraction for your combat ability, not just the raw amount of abuse your body can take. As you fight harder monsters, you have to learn more techniques to avoid being hit, but this is exhausting and you can't keep it going forever. These techniques also apply to simpler enemies. Getting a hit point is like adding one more technique to your repertoire.

I prove my point? Note that I didn't design this system, I inherited it from M59's previous developers, so I have no ego invested in this system.

Anonymous said...

In fact I liked the use based skill gain in Morrwind. You seem to forget that it had a stat gain added to it which sort of countered exploits. If I remember correctly you will gain a level for 10 skill gains in your primary skills. With each new level your stats will increase depending on the skills used.

So imagine you have a rogue character and try to gain levels by stealthing your char behind an NPC the whole night while you yourself are sleeping (like I did once). It works well as far as levels are concerened. Unfortunatley the only stat that increases will be your Dex (or whatever stat is appropriate). If you "walk the earth" however, with each level you will get an increase in strenmgth, stammina, whatever stat you used in gaining the level. Thats a good way to prevent a certain kind of exploitation.


evizaer said...

It's not about saying that use-based systems are good, but accepting that level-based systems don't avoid the points you're talking about by default.

I'm well aware that some of the same problems are shared between the systems. But use-based skill gain is less apt for dealing with these problems.

Use-based skill gain definitely does reward a very restricted set of actions--in fact, your M59 example shows how it is even MORE true than I thought in the "better" systems.

It's so much harder to dodge runaway positive feedback loops in use-based systems. Positive feedback does exist in classic advancement systems, but they are nowhere near as severe as in use-based systems because the scope that an experience point covers in class-based systems dilutes the positive effect to the entire character instead of just one ability.

Exploitation is a problem in class-based games, but it is worse in use-based systems principally because of the feedback loops becoming insane. If you even slightly have an unbalanced system, the players will exploit the hell out of the imbalance to level whatever skill to max in an extremely short period of time and you won't be able to reliably roll-back their exploited gains. Level-based systems don't run into this problem because you can't specialize your training in such a way.

You can certainly make a passable use-based system, but they seem to cause more design problems than they solve.

I think you're largely arguing semantics, Brian. I'm pointing out problems that are exacerbated by use-based skill gain, and you're trying to illustrate that I don't understand the scope of these problems in other systems. I don't think you've actually made an argument against what I'm saying, you're just pointing out what you think is me ignoring the failings of all game systems. Every system can be exploited if not designed well. Every system can have runaway positive feedback loops. I know that. It's also irrelevant to this article.

Brian 'Psychochild' Green said...

I'm too wordy. Damn the size limitations!

I think you're largely arguing semantics, Brian. I'm pointing out problems that are exacerbated by use-based skill gain, and you're trying to illustrate that I don't understand the scope of these problems in other systems.

No, you're missing the big point, and I was hoping you'd catch it with the M59 example: the M59 hit point system is an experience-based system in the trappings of a use-based system. Killing monsters = gaining experience points, except:

1. Experience points gained in this system only apply to hit points; you don't "level up" a bunch of attributes at once. You can earn experience for other use-based systems at the same time; there used to be a parallel system that awarded points for weapon skills in the same way.

2. M59's hit point system doesn't have a set reward threshold, instead it relies on a random element. Hooray random reward schedules!

Now, you might argue that you were referring to a "pure" use-based system without accumulated points. That's a strawman because no use-based system I know does that. Yes, that type of system is inferior and nobody uses it anymore.

It's not just "semantics" here (although meaning is VERY important), but the reality that the underlying systems are both similar except for some design choices. As M59's hit point system illustrates, the distinction between "use based" and "experience point based" advancement can be very thin.

So, assuming you'll accept that use-based systems have been contaminated with point accumulation, what are the primary differences between the two systems? I see two:

1. What actions points are awarded for.
2. What rewards a single pool of points can give.

In your typical use-based system, the pools are much narrower. In the extreme (and common case), you get one pool for each skill. In M59, you have a few general pools like hit points, and casting spells in each school.

In an experienced-based system, you generally have one pool (or a few pools for very broad areas... notice how we're already blurring the line here?) that rewards multiple areas when sufficient points are accumulated.

So, given this, let's look again at your original criticisms:

Rewarded for a narrow range of activities: Again, this can be true for either option. The original EverQuest only rewarded experience points for killing things in combat. There's nothing saying that you couldn't award points for things like talking to NPCs, doing related quests, or many other things.

Positive feedback loops: We can solve the positive feedback loop in both systems by restricting how advancement happens. In experienced-based systems the design handles this with the concept of "trivial" monsters. M59's hit point system does the same thing.

Exploits, macros, etc: Again, both systems fall prey to this. You can design a system for either to mitigate the affect of exploits, macros, etc. As I said above, though, an exploit that gives me points into a general pool is going to be worth more than an exploit that gives me points to one out of dozens of pools.

Immersion/metaphor: Again, it's the same metaphor because it's the same mechanic: adding points and getting rewarded when you have enough. One is not more immersive than the other at the core.

So, if you want to discuss the systems, start poking at the core design options and explain why one option might work better than others. There certainly are advantages and disadvantages to each, but let's talk about those instead of lumping a bunch of assumptions about some designs as currently implemented together for an incomplete discussion where most of it is defining what the systems mean.

evizaer said...

I grabbed hold of your big point when I was writing a huge comment here that I ended up replacing with "I'll post more on this later." I'm going to go into the character growth mechanics analysis significantly within the next few posts, so we should continue our discussion once that happens.