Exception-Based Design?

[Staffan]

The key problem with exception based design is that players must be familiar with all the rules there's an exception to. The simpler the system, the easier this is to achieve, but the fewer exceptions which can be made, which often leads to adding additional rules to compensate, which creates even more rules to make exceptions to.

It also helps if exceptions are made in similar ways. For example, in 3e there were a number of combat maneuvers a character could use against an opponent: trip, disarm, bull rush, sunder, feint, grapple, and so on. There were also a number of feats you could take to improve these, with either Combat Expertise or Power Attack as prerequisites. Most of these feats were similar in that they removed the AoO for trying one of these maneuvers and also providing a +4 bonus. Some also provided some other benefit – e.g. Improved Trip letting you get a free attack when knocking an opponent down, or Improved Disarm not risking getting disarmed back. But these extra benefits were different for each feat, making it kind of hard to remember what works in what way. And then there was Improved Feint, which instead made feinting a move action instead of a standard action – working in a completely different way.

That means that each of these feats require a separate info "slot" in the brain. But if they all worked the same way (+4 and remove AoO), and maybe had a separate upgrade feat that let them do something else, that would be less cognitive load.

To some degree this can be accomplished by using keywords. Keywords generally increase the up-front cognitive load, but reduce it over time. For example, there are a number of 5e spells that specifically make noise that can be heard up to 300 feet away. In a system with more keywords and less natural language, those would have a keyword like "noisy" so you wouldn't have to concern yourself with the noisiness of thunderwave or knock separately – you just know that a noisy spell can be heard 300 ft away.

 

[Thomas Shey]

Well I am not sure what common metric we're talking about. With any system you can have 'too much stuff' problems.

Its far, far less of a problem in games where things are constructed from extent components, because you don't have to spell out every case in detail. There are often also tools for covering more ground without having to acquire an entirely different ability for every distinction present. If "mind control" powers in a game work to a common metric, all you need to do when talking about two of them is spell out the ways they differ. If every mind control power is special case, then you can't do that.

 

[AbdulAlhazred]

Its far, far less of a problem in games where things are constructed from extent components, because you don't have to spell out every case in detail. There are often also tools for covering more ground without having to acquire an entirely different ability for every distinction present. If "mind control" powers in a game work to a common metric, all you need to do when talking about two of them is spell out the ways they differ. If every mind control power is special case, then you can't do that.

Yeah I think we're trying to say the same thing, exception based systems are easier to understand, vs designs like AD&D or even 5e where there's a different subsystem, or the exceptions are not really spelled out as such.

 

[dbm]

I would call what @Thomas Shey is describing an effects based system.

Even though Rob Heinsoo uses the label ‘exception based’ for the 4e structure, I would respectfully disagree. 4e is a pretty textbook example of effects based design, where the powers are built from a library of effects in different combination. That became one of the criticisms of 4e - that the abilities across classes were too similar; a risk with most effect-based systems. And recreating the AEDU structure in effect based systems like HERO or GURPS is very easy, which I would suggest backs up this point.

Naturally the potential cognitive load of effect based systems increases based on the number and range of effects. For players this only usually matters in character creation when the player has to pick from the full range of possible effects; during play they only have to remember the effects their character makes use of. The GM may need to know them all, however, and that can be tricky.

 

[Thomas Shey]

Yeah I think we're trying to say the same thing, exception based systems are easier to understand, vs designs like AD&D or even 5e where there's a different subsystem, or the exceptions are not really spelled out as such.

I think the problem, as has been true throughout this thread, is we're using the term "exception based" almost diametrically opposite.

 

[Thomas Shey]

I would call what @Thomas Shey is describing an effects based system.

Yup.

Even though Rob Heinsoo uses the label ‘exception based’ for the 4e structure, I would respectfully disagree. 4e is a pretty textbook example of effects based design, where the powers are built from a library of effects in different combination. That became one of the criticisms of 4e - that the abilities across classes were too similar; a risk with most effect-based systems. And recreating the AEDU structure in effect based systems like HERO or GURPS is very easy, which I would suggest backs up this point.

The problem is that 4e wanted to have its cake and eat it too, here. It was using what appeared to likely be an effect based underpinning, but it didn't want to actually tell you what that underpinning was (likely because it is not what people in the D&D sphere are used to, and as noted, sometime seem to actively dislike for purely emotional/taste based reasons). The net effect was the ability in most effect based systems to compact some similar mechanical elements to save space and cognitive load mostly wasn't there; all you had were the assembled chunks which ended up having at least 80% of the usual problem with exception based design, while still feeling samey to the people hostile to it.

 

[dbm]

it didn't want to actually tell you what that underpinning was (likely because it is not what people in the D&D sphere are used to, and as noted, sometime seem to actively dislike for purely emotional/taste based reasons).

I think that is a likely take. One of D&D’s strengths is being easy for players to pick up (which is a good thing) whereas effects based systems have a front-loading of complexity. Exposing the effects system would have been counter productive for D&D.

 

[Thomas Shey]

I think that is a likely take. One of D&D’s strengths is being easy for players to pick up (which is a good thing) whereas effects based systems have a front-loading of complexity. Exposing the effects system would have been counter productive for D&D.

That's at least somewhat fair. But at the point you've gotten at all far into an exception based system, the upfront savings get paid off with a vengeance, so it only really makes sense if you think that backend will never really get used or used so rarely it doesn't matter. Further, the front loading on learning an effect based system only really happens once, where you can take a long time repeating that backend payoff on exception based designs (watch the amount of time GMs running spellcasters have to spend looking up spell descriptions some time; they never use any of the often enough to get used to all the spells they may need to know unless they keep their palette very limited).

 

[Staffan]

The problem is that 4e wanted to have its cake and eat it too, here. It was using what appeared to likely be an effect based underpinning, but it didn't want to actually tell you what that underpinning was (likely because it is not what people in the D&D sphere are used to, and as noted, sometime seem to actively dislike for purely emotional/taste based reasons). The net effect was the ability in most effect based systems to compact some similar mechanical elements to save space and cognitive load mostly wasn't there; all you had were the assembled chunks which ended up having at least 80% of the usual problem with exception based design, while still feeling samey to the people hostile to it.

I never got any sense that there was an underlying cost system or something like that with 4e – only vague guidelines like "A 1st level weapon-based encounter power should do 2W with a minor effect or 1W with a significant one". What it did have was keywords and conditions galore, and often pressed these keywords into service in ways that felt a bit off, such as a power that instilled fear in its targets which was translated as a push.

 

[dbm]

at the point you've gotten at all far into an exception based system, the upfront savings get paid off with a vengeance, so it only really makes sense if you think that backend will never really get used or used so rarely it doesn't matter

I think with D&D the appearance of complexity at character creation is a negative in its own right to a big chunk of the (usually casual) fans. So the normal cost / benefit analysis is skewed heavily towards hiding complexity and drip feeding it into play.