What makes an RPG good?

[Sneak Dog]

A good game is fun to play.

I was tempted to leave it there to make it a statement about the simplicity of it all. But then I thought I should explain that whatever general criticism you can level at a system doesn't really matter as long as people are enjoying it. You can argue that maybe they would have more fun with a different game but even if that is true the second game is merely better not that the first is bad. And I suppose I am ignoring some special purpose games that don't exist for entertainment… yeah that's fine for now.

Let me close off with some things that generally help systems be fun:

• Clear about their goals. (Expectation/Experience matching.)
• Have unity between there mechanics and themes.
• They should take minimal time/energy/skill to learn (minimal is relative and I am speaking of the skill floor).
• They should take minimal time/energy/skill to play/run (same, this one is surprisingly controversial).

Actually the last two are so broad they kind of cover everything else I was going to put on the list.

Just 'fun to play' is not a useful metric. We can't measure short-term fun very well, it gets muddied by playing a game with friends being fun. Long-term fun is even trickier, little frustrations might add up and ruin the experience. Then we get to the part where a TTRPG is not a game, but a system for a GM to make a game out of, and how to split the GM making a fun game from the system being fun.
The list is important. It lets us actually figure out what makes an RPG good with something we can talk about.

Good first two points.
Requiring time to learn is a barrier to entry, but the results can well be worth it. It's a trade-off. Striving to minimise time/energy/skill is good, but can be sacrificed for other aspects and make the RPG better. I agree it generally helps.

Requiring energy and skill to play is straight-up great though. It lets you get into the game and get rewarded for investing effort and being skillful and penalised for the opposite. Plenty of players enjoy this challenge and would have less fun without both reward and penalty. This is a playstyle thing which would (probably) make it bad for you, but good for others. So it doesn't apply, as you say, generally.

[Cluedrew]

Just 'fun to play' is not a useful metric.

I'm not claiming we can measure it, but it is more important than anything we can measure.

Requiring time to learn is a barrier to entry, but the results can well be worth it.

This is what that note about relative is all about. I'm not disagreeing but I did think of that. In this phrasing I would say for a given set of goals if you can lower the barrier to entry you should.

Requiring energy and skill to play is straight-up great though. It lets you get into the game and get rewarded for investing effort and being skillful and penalised for the opposite. Plenty of players enjoy this challenge and would have less fun without both reward and penalty. This is a playstyle thing which would (probably) make it bad for you, but good for others. So it doesn't apply, as you say, generally.

This I don't understand. If I explained I was speaking of the "floor" (minimum required to get a reasonable result) verses the "ceiling" (where improvements in stop getting improvements out). Its always nice to improve but I think mastery/challenge is only really core in the commonly included combat mini-game. Which, for all the many people who have fun playing it, is a good bit of design. For me, those flavours don't mix.

[Tanarii]

This I don't understand. If I explained I was speaking of the "floor" (minimum required to get a reasonable result) verses the "ceiling" (where improvements in stop getting improvements out).[/COLOR]

Right. If something has a high energy requirement to play, I'm going to play it only once in a blue moon. If something has a high skill requirement to play, I'm not going to be able to find any new players to play with me. This is a surprisingly common barrier in Board games too.

TTRPGs almost always have an extremely high time requirement to play. It is hands down the hardest part about getting long term players and IMO the thing that keeps it from growing as a casual entertainment field.

About the only east way you'll get players for high skill/time to play is if you participate in dedicated gaming clubs regularly. E.g. Game stores or school campuses.

[Witty Username]

Other people who are willing to play with you is what makes an RPG good.

[Yora]

That is literally the lowest possible measure of something's quality.

[Altheus]

Easy to teach to others, quick to play and not that many character build options.

[Jason]

THAC0 is the poster child for a dis-intuitive mechanic that smart people couldn’t grasp because it ran negative to every other mechanic in the game. (I know people defend THAC0, but if it was so good why has it been abandoned and no other game stile the concept?)

THAC0 was not at all difficult to figure out, and was a definite step up from having to look at the chart in the DMG.
Most games today have a mechanic that is very like THAC0. Basically any rule that says "it's this hard to hit this NPC" and requires addition and subtraction is just as difficult to figure out as THAC0 was. I could say something about what thinking a little addition and subtraction is too complicated to grasp says about ths average gamer's math skills today, but I will refrain.

[Yora]

"If BAB had been used from the start, nobody would ever have seen a need to invent THAC0."

That's always the end of discussion to me.

[Jason]

"If BAB had been used from the start, nobody would ever have seen a need to invent THAC0."

That's always the end of discussion to me.

True, but BAB is just THAC0 with the "subtract from 20" step already done. Its not really a brand new mechanic.

Fun fact: to convert an Armor Class from 1st or 2nd edition to 3rd-5th edition, subtract it from 20. To convert from 3rd-5th edition to 2nd or 1st edition, subtract it from 20. It works either way.

[MoiMagnus]

True, but BAB is just THAC0 with the "subtract from 20" step already done. Its not really a brand new mechanic.

Which makes BAB significantly better as a rule than THAC0.

Quite often, when you rework a mechanics, you're not making raw improvement, you're making some trade-off. You're sacrificing a lot some depth or granularity for the sake of simplicity, etc.

When reformulating, you can actually obtain something which is objectively better, rather than just a different tradeoff than the existing one. (Though arguably, there is some trade-off, like confusing old time players, but they are much milder)

[Tanarii]

That is literally the lowest possible measure of something's quality.

Popularity isn't lowest, it's just a quick yardstick.

It's not always the most accurate though. There are a ton of people that subscribe to Any Gaming is Better Than No Gaming (and Boredom). Or are reasonable compromisers, willing to play something they consider sub-par but not terrible that are all others know, in order to get games.

THAC0 was not at all difficult to figure out, and was a definite step up from having to look at the chart in the DMG.

The game lost a lot in subtlety when it changed to "20 always hits 1 always misses" but it definitely gained in ease of play.

[Jason]

Which makes BAB significantly better as a rule than THAC0.

Yes it is easier to use, but it really is the same mechanic, just expressed a little more simply.

My point being that THAC0 is not the impenetrable mystery that many gamers who never played with it make it out to be. At the time it was introduced it was a useful innovation that was much easier and quicker than what was used before.

You want impenetrable, try to figure out what the "advantage" symbol in FFG Star Wars is supposed to represent. "Using custom dice with non-intuitive symbols that no one can figure out what they are supposed to be" is one of my criteria for a bad game.

[kyoryu]

An RPG is "good" when it effectively delivers on the things it's trying to (intentionally or accidentally) deliver.

It's good for you when the things it delivers on are things you want.

THAC0 was not at all difficult to figure out, and was a definite step up from having to look at the chart in the DMG.
Most games today have a mechanic that is very like THAC0. Basically any rule that says "it's this hard to hit this NPC" and requires addition and subtraction is just as difficult to figure out as THAC0 was. I could say something about what thinking a little addition and subtraction is too complicated to grasp says about ths average gamer's math skills today, but I will refrain.

Arguably.

The advantage of the chart is that it allowed for (and actually had) non-linear changes to chances to hit, which a formulaic approach like THAC0 or BAB does not.

The disadvantage of course is that you have to look it up, which means you need a quick reference and a brief second of time on each hit. So.... it's a matter of which of those things matters more to you.

Popularity isn't lowest, it's just a quick yardstick.

It's not always the most accurate though. There are a ton of people that subscribe to Any Gaming is Better Than No Gaming (and Boredom). Or are reasonable compromisers, willing to play something they consider sub-par but not terrible that are all others know, in order to get games.

Popularity does not directly correlate to quality, but it's hard to have a lot of popularity without having at least a good amount of quality.

Like, a game being unpopular could be really awesome, just unknown for various reasons.

But a really popular game probably has at least some good stuff going for it (yes, even 4e).

But that's really quality in the first sense of what I wrote above... a popular game could still be terrible to you because the things it does well are things you have no interest in, or even actively want to avoid. Like, that's me and country music and most pop. I can recognize the talent of the people doing it, while still acknowledging that they're just doing things I have zero interest in.

That's also me and D&D 3.x. It's a great system for doing a bunch of things that are the opposite of what I consider to be ideal gaming.

THAC0 was not at all difficult to figure out, and was a definite step up from having to look at the chart in the DMG.
Most games today have a mechanic that is very like THAC0. Basically any rule that says "it's this hard to hit this NPC" and requires addition and subtraction is just as difficult to figure out as THAC0 was. I could say something about what thinking a little addition and subtraction is too complicated to grasp says about ths average gamer's math skills today, but I will refrain.

At one level you're right, but THAC0 doesn't present that concept well.

You've got: AC, how hard you are to hit, lower is better. (Why?)

THAC0, which represents how likely you are to hit stuff..... lower is better.

Now, you subtract AC? THat's weird. It's just not intuitive. And then you have a roll over system.

Yes, all the bits are still there that are in there with BAB, but it's just more obvious how to use them "they have a number to beat. Roll over it, and add all the stuff that makes you better. If they have stuff that makes them harder to hit, they add it to the number to beat." Like, there's an intuitiveness of why things are that way that just works.

The only reason for THAC0 to be the way it is is to keep compatability with 1e, whose system was a holdover from other games. It's not really defensible as a system in a green field environment.

It's also not as horrible as a lot of people seem to make it out to be, especially if you accept it just as a formula you use, rather than trying ot "understand" it.

[Tanarii]

You've got: AC, how hard you are to hit, lower is better. (Why?)

This one is easy. Because lower is tougher to hit. (That statement depends on the system obviously, but it make intuitive sense.) Impossible to hit should be zero though, negative AC numbers don't make sense.

THAC0, which represents how likely you are to hit stuff..... lower is better.

This one is just an artifact of the attack tables. It makes sense that higher is better attacking.

[kyoryu]

This one is just an artifact of the attack tables. It makes sense that higher is better attacking.

Well, yeah.

The only reason for THAC0 to be the way it is is to keep compatability with 1e, whose system was a holdover from other games. It's not really defensible as a system in a green field environment.

It wasn't designed as a good system in and of itself - it was designed as a chartless variation of the attack tables from 1e.

[Pauly]

THAC0 was not at all difficult to figure out, and was a definite step up from having to look at the chart in the DMG.
Most games today have a mechanic that is very like THAC0. Basically any rule that says "it's this hard to hit this NPC" and requires addition and subtraction is just as difficult to figure out as THAC0 was. I could say something about what thinking a little addition and subtraction is too complicated to grasp says about ths average gamer's math skills today, but I will refrain.

Just because I’m on the interwebs doesn’t mean I’m some whippersnapper in short britches. I learned to play Chainmail from on original store bought copy before I learned D&D.
If what I wrote was too complicated to grasp it says a lot about the average gamer’s reading comprehension skills today, but I will refrain.
I specifically said the math itself wasn’t difficult. What is difficult conceptually is that in the rest of the game mechanics high numbers represent stronger/more difficult and positive modifiers are good. Yet armor class/THAC0 reversed that. Your +1 sword made your THAC0 smaller, which was good. Your cursed armor +1 made your AC higher, which was bad.

To be conceptually easy to understand, intuitive in other words, a game should use
High numbers good, low numbers bad, or
Low numbers good, high numbers bad.
Mixing and matching between the two is bad design. It isn’t about the difficulty of the math, it’s about the consistency of the math.

It applies to other things. For example agility skill tests should use the same mechanics as diplomacy skill checks. Roll a d[whatever] add your bonuses subtract your penalties. Consult the outcomes table and success/fail. But if your diplomacy check and agility check require different dice, different tables for success then it becomes conceptually difficult.
It would be like driving a car only for the brake and accelerator pedals to be reversed depending whether you were turning left or turning right. There might be good reasons why it’s a better system, but it will confuse the heck out of the driver.

[Pauly]

It wasn't designed as a good system in and of itself - it was designed as a chartless variation of the attack tables from 1e.

Having played those, the charts were easier to understand, the THAC0 easier to use.

[Witty Username]

Which makes BAB significantly better as a rule than THAC0.

Quite often, when you rework a mechanics, you're not making raw improvement, you're making some trade-off. You're sacrificing a lot some depth or granularity for the sake of simplicity, etc.

When reformulating, you can actually obtain something which is objectively better, rather than just a different tradeoff than the existing one. (Though arguably, there is some trade-off, like confusing old time players, but they are much milder)

THACO does come with an advantage that you can roll and immediately know whether or not you hit, If you roll over your THACO, you hit (true 90% of the time). BAB you have to calculate what your number was every time to determine if you hit or not, assuming AC is hidden from the players. This allow comes with the 10% of the time THACO doesn't hit, you know you are dealing with one of the better AC's in the game, instant panic. YMMV on how important this is, but I personally like how THACO puts emphasis on the characters skill rather than the monsters defenses it makes ones combat prowess easier to grok (even if it is only a little). That being said I have been aware of THACO and how to use it since I was ~6, so it may be more out of familiarity than effectiveness.

[Tanarii]

I specifically said the math itself wasn’t difficult. What is difficult conceptually is that in the rest of the game mechanics high numbers represent stronger/more difficult and positive modifiers are good. Yet armor class/THAC0 reversed that. Your +1 sword made your THAC0 smaller, which was good. Your cursed armor +1 made your AC higher, which was bad.

Saving throws, lower numbers were better, because you had to roll over them.

Ability score checks (E.g. BECMI RC's general skills, or Ad&D's NwP), higher numbers were better, because you had to roll under them. Unless you had a closer to threshold check (opposed rolls), in which case higher number rolled but still succeeded was better.

Thieves skills were on d%, while reaction rolls were 2d6, and Surprise checks were on a d6, unless they weren't.

IMO the attack matrix was superior to THACO, but it was pretty much in line with the rest of the system: no consistent expectations should be assumed.

[Jason]

Saving throws, lower numbers were better, because you had to roll over them.

Yep. It's not the case that higher numbers were always better in 1st ed. AC was not the only example of this, merely one of the more prominent ones.

Cursed armor was described with negative numbers (-1, -2, etc.) In 1st edition. +1 Armor is beneficial, and would lower your armor class, not raise it.

The idiosyncrasies of the system were frankly part of the charm.

[Telok]

You know... I'm going to say that specific mechanics like thac0 don't make a game good or bad. Simpler or more complicated perhaps. Easier or harder for some. Which could be better or worse for individual people. I mean, at least it's not <gasp> dividing by 3 or something. The horror. The horror.

If you equate "all rolls use the exact same mechanic" and "minimum complexity" with a "good game" then there's a pile of games out there that use a single d6 and a handful of pages. One mechanic, total simplicity, no math beyond adding or subtracting single digits. And nobody ever mentions them or serms to play them despite them checking all the "good" categories.

But I can still find groups having a blast with AD&D, ShadowRun, and Champions. All of which are "bad" games by those metrics. Of course that's back to fun/popular not making a game good. That tells me there's a range of complexity and disparate mechanics that matters. A number of games are possibly too simple, as a number may be too complex. Of course people will rate things differently based on personal preference.

D&D has never had a truely unified mechanics (damage, occasional d100 charts, & needing to use multi-roll checks to even out certain situations, off the top of my head) and there are things which the d20+X vs DC paradigm isn't great and needs the DM to fix during game. Plus, frankly, it still isn't anywhere near simple or easy in a fair number of places.

So I'd say that a negative point on the good-bad game meter is unwelcome complexity that that fails to produce a commensurate benefit. Likewise a positive point would be simplicity that doesn't sacrifice some aspect of game play just for the sake of simplicity.

I'm really thinking that it's not really useful to just say "good" or "bad". It needs to be "good for-", "bad at-", and "does/doesn't need advanced DM skills to-".

[Satinavian]

You know... I'm going to say that specific mechanics like thac0 don't make a game good or bad. Simpler or more complicated perhaps. Easier or harder for some. Which could be better or worse for individual people. I mean, at least it's not <gasp> dividing by 3 or something. The horror. The horror.

Thac0 is not bad because it is complex or hard to understand. It is bad because it is needlessly complex. It doesn't provide any benefits over simpler menachics that can reach the very same outcomes. Like BAB.

[Pauly]

You know... I'm going to say that specific mechanics like thac0 don't make a game good or bad. Simpler or more complicated perhaps. Easier or harder for some. Which could be better or worse for individual people. I mean, at least it's not <gasp> dividing by 3 or something. The horror. The horror.

If you equate "all rolls use the exact same mechanic" and "minimum complexity" with a "good game" then there's a pile of games out there that use a single d6 and a handful of pages. One mechanic, total simplicity, no math beyond adding or subtracting single digits. And nobody ever mentions them or serms to play them despite them checking all the "good" categories.
to-".

Since I brought up THAC0, the complaint about it isn’t the mechanics. The math works. I prefer high numbers good, low numbers bad, but I can work with low numbers good, high numbers bad.
The complaint is that it is inconsistent with the rest of the game. People found the inconsistency difficult, not the mechanic. People could see that what we know ad BAB would work without forcing your brain to remember a different subsystem for that circumstance.

It isn’t about simplicity. Different games offer different levels of complexity to different groups. I’ve played and enjoyed Empire, a TT wargame where the quick reference sheet was 12 densely typed double sided pages, and you needed all of that to play the game in anything resembling a timely manner.

When playing a RPG your time is split between the RP (the story) and the G (the mechanics). The more time you devote to the G the less you can put into the RP. If your mechanics are consistent then it helps players streamline their thinking and decision making.

[Tanarii]

The complaint is that it is inconsistent with the rest of the game.

It really wasn't though. Low THAC0 (or to-hit number on a chart) was better, low saving throws were better, and low AC was better. It was actually fairly consistent, in so far as the word could be applied to AD&D, which it can't.

The game was structurally full of inconsistent subsystems for resolution. But "higher is better" wasn't the case.

It also makes conceptual sense for it to be lower. Thac0 is a TN, like saves. And later, like DCs. And for TNs where the goal is to roll over, lower is better.

What actually changed was AC was turned onto a TN. Originally, it wasn't.

[Jason]

You know... I'm going to say that specific mechanics like thac0 don't make a game good or bad. Simpler or more complicated perhaps. Easier or harder for some. Which could be better or worse for individual people. I mean, at least it's not <gasp> dividing by 3 or something. The horror. The horror.

If you equate "all rolls use the exact same mechanic" and "minimum complexity" with a "good game" then there's a pile of games out there that use a single d6 and a handful of pages. One mechanic, total simplicity, no math beyond adding or subtracting single digits. And nobody ever mentions them or serms to play them despite them checking all the "good" categories.

But I can still find groups having a blast with AD&D, ShadowRun, and Champions. All of which are "bad" games by those metrics. Of course that's back to fun/popular not making a game good. That tells me there's a range of complexity and disparate mechanics that matters. A number of games are possibly too simple, as a number may be too complex. Of course people will rate things differently based on personal preference.

That's the thing. Some groups like complex, while others don't. Some groups even like "needlessly complex". There are fans of Starfleet Battles because of the giant rulebook. There are gamers who spend endless hours using the MegaTraveller and Traveller the New Era and GURPS Vehicles rules just designing vehicles and starships.

Ever looked at the vehicle combat rules for the original Twilight: 2000? Challenge Magazine published a TW2K combat example in the late '80s. In the example, a group of players has holed up in a Polish farmhouse, when a group of marauders come by and decide to bushwhack them. During the course of the battle one marauder fires a portable anti-tank missile at the player’s Bradley armored fighting vehicle. This is how the attack is resolved:

Second Turn, Round Three: The sniper fires the Armbrust. At 100 meters (close range) his HW 60 means he needs to make a percentile roll of 36 (at close range the percentage to hit is 0.6 times base skill). He rolls 34 and hits.

It is a left front oblique shot, and the oblique column of the vehicle hit location chart is used. A die roll of 5 is a F:HS or center hull side result (per the notes to the aforementioned chart). Consulting the vehicle damage location list for the M2 Bradley APC, the referee notes that the armor at that point is 15 (the number in parens after the F:HS). The referee then determines damage (per pages 8-10). According to these rules, the damage of the weapon is compared to the target's armor at the location of the hit (15 in this case). The Armbrust damage is x 20C. The x means the damage (20) is multiplied by a die roll. The C (for constant) means this die roll does not vary with range and is always 4D6 (4D6 is the damage roll for weapon attacks at close range). A 4D6 roll of 17 multiplied by 20 is 340 damage points for the Armbrust. Since the Armbrust's damage is greater, the weapon penetrates with 325 damage points remaining.

The component list for the Bradley at location F:HS is D,E,F. This is the order in which the components take damage if the vehicle is hit from the right side. For a left side hit (such as this one) the order is reversed, and becomes F,E,D. In the notes to the vehicle damage hit location tables, we see that these letters represent the vehicle's fuel, engine, and driver. The damage points remaining after penetration hit each of these in sequence, with fuel first. This follows the procedure outlined in the component damage rule (page 9).

First, the referee consults the damage multiplier table (referee's charts) and notes that the damage multiplier of fuel is x 10 or 10.

Second, the two numbers (remaining damage and damage multiplier) are compared. Since 325 is greater than 10, the shot damages the component. The referee subtracts the multiplier from the damage, leaving 315 damage points.

Third, the damage points left over are multiplied by 10 to determine the percent damage (315 x 10=3150%).

Fourth, the actual number of hits taken by the fuel is determined. For every 10% damage the component takes, it receives actual damage points equal to its damage multiplier. In this case, that is 3150/10 = 315 x 20 = 6300. This is subtracted from the remaining damage figure to determine if any energy goes on to other components; 315-6300= - 5985, (page 9). The Armbrust has expended its energy, and no other component is hit.

There is a special case for the referee to consider, however: fuel can catch fire. The fuel hits rule (page 10) states that if the percent damage to the fuel is greater than or equal to the flashpoint for that particular type of fuel (taken from the fuel flashpoint table in the referee's charts) the fuel catches fire. The referee looks up the flashpoint for the ethanol fuel the Bradley is carrying (30%) and tells Allen that the Bradley is on fire.

Allen must now try to escape. Ordinarily this would be a AVG:AGL task, but the referee rules that Allen is wounded and increases it to DIF:AGL. This means that Allen must make a percentile roll less than or equal to half his converted AGL. Allen's AGL is 12, which converts to 60. Allen must roll 30 or less to escape unharmed. He rolls a 41 and escapes, but he is burned in the process. Per the escape rule (page 10) the referee rolls ID6 for the number of locations burned (getting a result of 3), rolls each location on the hit location chart, and finally rolls 1D6x ID6 for damage to each area. Allen receives 12 points of damage to his left arm, 8 points of damage to his abdomen, and 16 points of damage to his left leg. Since his left leg has already taken 9 points, this is a total of 25 points, which is greater than the left leg's hit capacity of 19, but not more than twice that capacity. This is a serious wound, and Allen must roll against his CON to remain conscious (55 or less). He rolls 23 and can still move (a good thing, since remaining next to a burning Bradley is not a good thing), but only at a crawl since his left leg is seriously wounded (all that is stated in the rules is that he would lose use of the limb, but the referee uses his common sense, and restricts Allen's movement in this way). Allen must make the roll to stay conscious each turn he crawls away from the burning Bradley.

Yeah.

That game was pretty popular in its day. I imagine reading that example alone could make the brains of gamers who think THAC0 is needlessly complicated explode.

Complexity is therefore by itself not an objective criteria of whether a game is bad or good. How much complexity is good or bad depends on the group and the amount of crunch they like in their rules..

[Telok]

Ok, thac0 was the number the player needed to roll to hit an armored target. Just like the ad&d saves were the number the player needed to roll to survive by dumb luck and fate after they messed up. The dm told the player a modifier, if any. The numbers on the ad&d character sheet were the numbers on the die that the player needed to roll, ac was a modifer to the opponent's roll. The thing that changed was the ac modifier got wrapped into the dc instead of the roll.

It's not particularly good or bad as a mechanic, just poorly explained.
d20+(player mods)+(enemy ac bonus) vs 20
d20+(player mods) vs 20-(enemy ac bonus)
And of course 20-8 = 10+2. Who wrote down what the roll needed to be just moved from the players to the dm.

Mechanically it's the same, the difference is presentation and explanation. The later d&ds were better with the presentation, the mechanic didn't change. Its about the same style difference as physics equations taught as algebra vs taught as calculus, same numbers with different style.

Enough. Thac0 is old news and all this has been gone over before. I'm gonna let this die. I think bell curve systems are better for not-comedy games. Dosen't make them better for everything and not all bell curve systems are better than flat distribution systems.

[Stonehead]

You know... I'm going to say that specific mechanics like thac0 don't make a game good or bad. Simpler or more complicated perhaps. Easier or harder for some. Which could be better or worse for individual people. I mean, at least it's not <gasp> dividing by 3 or something. The horror. The horror.

For sure one mechanic can't make a game good or bad, but surely there's more granularity than that when judging a games quality, right? THAC0 was before my time, so I can't really comment on it's quality as a rule, but lets pretend everyone agrees it's bad for a second. If THAC0 was replaced with something more intuitive, that wouldn't have automatically made AD&D a good game, but it would have made it better.

There's been a lot of talk in this thread about how well systems deliver on their promises, and a game's rules are one of the biggest ways it does that.

[Quertus]

Well. THAC0 got interesting.

So, in d20 systems, the target number (DC) is how difficult the challenge is, your skill is the modifier added to the d20 of chance to see if you succeed. Rolling high is good.

In 2e, your skill (THAC0, saves) is your target number; the challenge (AC, save bonus/penalty) provides the modifier added to the d20 of chance to see if you succeed. Rolling high is good.

But then, in 2e, your attribute is the target number for skill checks, the particular skill and the challenge provide the modifiers… to the target number… and you roll the d20 of chance to see if you succeed. Rolling low is good.

For consistency, the 3d6 base stats should have been reversed, low numbers should have been good. Fighters should have required a 12 or lower Strength, a Girdle of Storm Giant Strength should have granted a Strength stat of -3, and exceptional Strength should have looked like "3(100)" or something. Wizards should have hoped for a 3 in Intelligence (and want to use wishes to make it lower), etc.

Then everything in 2e would have been consistent. (Well, except psionics, and Thief skills, and…)

But, consistency aside, as much sense as "your skill (THAC0) is the target number, the challenge (AC) provides the modifier" makes, I'll contend that this is the first time I've seen the concept expressed so clearly.

Gygaxian pros aren't the only flaw in 2e's language, I guess. But it explains why AC was bounded (in roughly a +12 to -12 range).

[Jason]

For sure one mechanic can't make a game good or bad...

Giving it some thought, I think you're correct that one good mechanic won't make a whole game system good, but I think that one bad mechanic can make a game bad, especially if it's a very important mechanic.

For example, I don't like the basic dice mechanics for FFG Star Wars. I think the dice symbols are non-intuitive, it takes too long to build the pool and adjust it and then sort out the roll after youve rolled it, and then I dislike how almost every roll ends up a mixture of success and failure, and more often and to more extreme levels the more experienced your characters are.

That's the game's basic resolution mechanic. If you're annoyed by it, like I am, then you're going to be annoyed everytime you try to do anything in the game. That one mechanic ruins the whole game for me.

[PhoenixPhyre]

Giving it some thought, I think you're correct that one good mechanic won't make a whole game system good, but I think that one bad mechanic can make a game bad, especially if it's a very important mechanic.

For example, I don't like the basic dice mechanics for FFG Star Wars. I think the dice symbols are non-intuitive, it takes too long to build the pool and adjust it and then sort out the roll after youve rolled it, and then I dislike how almost every roll ends up a mixture of success and failure, and more often and to more extreme levels the more experienced your characters are.

That's the game's basic resolution mechanic. If you're annoyed by it, like I am, then you're going to be annoyed everytime you try to do anything in the game. That one mechanic ruins the whole game for me.

If I may, I'd change that to "one bad core mechanic can make a game bad for a person...". Then I'd be in agreement.

For example, I think that 5e's variant encumbrance is wack. Horrible. Not so much the idea, but that they got all the weights wrong so clerics built according to the quick-start guidelines are encumbered simply by wearing the gear they're provided. Not even the adventuring pack, just the armor and weapon. I'll never use variant encumbrance. That said, it's decidedly not a core mechanic, so meh. Doesn't affect my estimation of the system as a whole.

If they'd have set the core d20 + mod vs DC thing to be say "roll 1d20, do some calculus to figure out which table to roll on, then roll on that table (and each table uses a different pattern), which tells you which other table to use (once you factor in the phase of the moon)...", I'd say the whole system is bad (for me).

And that second italics is important. There are only a very few things that can make a system objectively bad. If the system itself just doesn't work at all (such as if you're missing critical parts of generating a character or the rules for doing so are internally contradictory so its impossible to make a legal character). A few things like that. But that's a really easy bar to clear. Beyond that, it's mostly a matter of taste and what works for you, personally, based on the things you're trying to do with it.