My 6 year old spontaneously declared that 8+ on d20 was the number needed for success. That seems built in to 4e D&D which operates around 8+ as the typical target number for player rolls. That's a 65% chance, very close to the two-thirds number. So I'd suggest that.

Thank you guys for your insightful responses.

Quote from: RandallS;687767On the original subject of this thread, I find the concept of some type of success/failure rate one can design around alien. Success in my campaigns is based as much (or more) on what the players have their characters do as what is written on the character sheets. According to their character sheet, a low level thief might only have a 20% chance of walking up to someone and picking their pocket.

Yeah, that was an issue I had in an Old School game I was running. Players were playing too much by the book.

Quote from: RandallS;687767However, that only means the character has an 80% chance of failure if that's all the character does: walk up and try to pick the victim's pocket. If the player talks other characters into distracting the victim, the chance of success will go up. If the character makes the attempt in a crowd where everyone is getting jostled, the chance will be higher, if there is that large crowd and  other PCs distract the victim, the chance of success will go up even more, etc.

In games were player skill is intended to be as or more important than the exact chances of success on the character sheet, the high starting values suggested by game theory (such as the 66% chance mentioned earlier in this thread) would basically mean auto-success if the players used player skill in the way I mentioned in the previous paragraph.

Quote from: The Traveller;687573My experience has been that players will stick with it if challenges require them to use their heads beyond just rolling a dice (ie wearing soft wool footpads rather than boots to help sneaking, hence the term footpad), so make sure the system allows for adjustments to rolls on that basis.

I guess the game I'm designing will go in that direction, i.e. low base chance of success that gets better with the players' ingenuity and roleplay.

Quote from: jerzyab;687821I guess the game I'm designing will go in that direction, i.e. low base chance of success that gets better with the players' ingenuity and roleplay.

Well no need to make it terribly low as a base, I usually give players the opportunity to start out characters good or very good at their specialities and pretty average at everything else. That way they can take on challenges which non-adventurers are guaranteed to fail at.

For example a master thief might have 200% in pick locks, but a god-fashioned lock might have a -120% modifier. A normal thief or even a very good thief would have zero chance of opening that, but the master lockpicker has an 80% chance. Lesser locks pop open if he looks at them crossways, but that doesn't make him hugely powerful, just a really good lockpicker, which is what makes him special as a PC.

Almost everyone starts out very competent in combat though, and rightfully so considering they will almost certainly be facing either large numbers of enemies or much more powerful enemies. or possibly both. While individually they might be a match for all but the top 1% of human warriors, an angry mob or a swooping dragon spitting flames can still take them down, so they need all the edges they can get on that front.

That last depends on the type of system you're setting up of course.

I have found that the level of success that keeps players the most engaged is whatever level they achieve via their own decisions & strategies.

In a roleplaying game limited only by your imagination, who wants to be told that they will just have to suck it 33% of the time to maintain interest?

If everything is based on percentages and the raw numbers I'm not going to be very invested at all no mater what the ratio is because my decisions in actual play have fuckall to do with victory or defeat.

Quality of player moves & decisions should be the primary factor in determining success. The game is for the player to win or lose not some formula.

So you're saying that if players are looking to succeed more often, they'll seek out lesser challenges, and if they're looking to fail more often, they'll seek out greater ones?

There is a lot of merit to that idea. If the players seem dissatisfied, giving them opportunities to go after alternate difficulty levels is probably a great idea.

But that doesn't answer the question of what the default position of the dial should be.

You know, I suppose you could just ask the players how hard they want it to be. To be honest that had never before occurred to me.

Quote from: Doccit;688124So you're saying that if players are looking to succeed more often, they'll seek out lesser challenges, and if they're looking to fail more often, they'll seek out greater ones?

There is a lot of merit to that idea. If the players seem dissatisfied, giving them opportunities to go after alternate difficulty levels is probably a great idea.

But that doesn't answer the question of what the default position of the dial should be.

You know, I suppose you could just ask the players how hard they want it to be. To be honest that had never before occurred to me.

There is no "dial", thus there can be no default position. Difficulty is a simple matter of risk vs reward. Smart players can assume more risk and still win.

But how are they supposed to know what is risky without testing themselves? If you're a level one, how are you supposed to know if you can take on goblins or rats? And if you'll get TPK'd fighting goblins when you assumed you could beat them, that isn't a very rewarding experience.

Quote from: Doccit;688177But how are they supposed to know what is risky without testing themselves?

Sometimes that's the only way to find out. In the right circumstances even 1 hp baby giant spiders can cause a TPK.

Tickled to Death by Tiny Spiders: TPK

Quote from: Doccit;688177But how are they supposed to know what is risky without testing themselves? If you're a level one, how are you supposed to know if you can take on goblins or rats? And if you'll get TPK'd fighting goblins when you assumed you could beat them, that isn't a very rewarding experience.

Before you can assess appropriate risks & rewards there needs to be objectives of play. In plain terms , what is a victory condition?

If the objective is to fight things, and you are very fragile but improve over time, then a sound strategy is to seek out only the weakest opponents until some measure of improvement has taken place. This is a very one dimensional approach because there is too little benefit to be gained from taking any risks.

If the objective is to win treasure, more strategic options open up. Fighting is still dangerous but no longer required to "win". You can then risk the possibility of a more dangerous fight for the chance to find better treasure but a life-ending death struggle isn't required to achieve victory.

Quote from: Exploderwizard;688109I have found that the level of success that keeps players the most engaged is whatever level they achieve via their own decisions & strategies.

In a roleplaying game limited only by your imagination, who wants to be told that they will just have to suck it 33% of the time to maintain interest?

If everything is based on percentages and the raw numbers I'm not going to be very invested at all no mater what the ratio is because my decisions in actual play have fuckall to do with victory or defeat.

Quality of player moves & decisions should be the primary factor in determining success. The game is for the player to win or lose not some formula.

I agree with this, and I'm going to suggest that this means that in terms of rolled chance of success, it is fine to have up to 100%.  A 100% success rate doesn't mean that there is no challenge.  It means that the challenge is in choices that the players make (or perhaps in their degree of success) rather than in their rolls.  

A good example is D&D spells.  Some systems require skill rolls for spells, but many D&D spells have 100% success - like Magic Missle, Light, Cure Light Wounds, etc.  Being able to cast Magic Missle with 100% of casting and 100% hit rate doesn't make a magic user boring - it means that he has to choose carefully when and how to use that.  You don't need to spell failure chance for magic use to be challenging.  

That said, I think it's fine to have a failure chance for verisimilitude purposes.  In real life, sometimes a safecracker won't be able to crack a given safe.  However, I think it is a misconception that the failure chance is needed for challenge.  Challenge to the players doesn't come from chance of failed rolls - it comes from consequences of their decisions.

Quote from: jhkim;688268I agree with this, and I'm going to suggest that this means that in terms of rolled chance of success, it is fine to have up to 100%.  A 100% success rate doesn't mean that there is no challenge.  It means that the challenge is in choices that the players make (or perhaps in their degree of success) rather than in their rolls.  

A good example is D&D spells.  Some systems require skill rolls for spells, but many D&D spells have 100% success - like Magic Missle, Light, Cure Light Wounds, etc.  Being able to cast Magic Missle with 100% of casting and 100% hit rate doesn't make a magic user boring - it means that he has to choose carefully when and how to use that.  You don't need to spell failure chance for magic use to be challenging.  

That said, I think it's fine to have a failure chance for verisimilitude purposes.  In real life, sometimes a safecracker won't be able to crack a given safe.  However, I think it is a misconception that the failure chance is needed for challenge.  Challenge to the players doesn't come from chance of failed rolls - it comes from consequences of their decisions.

Yarp. I think the idea of a challenge that always hinges on a die roll or series of rolls is ingrained in some gamers. It isn't badwrongfun to play like this but it does limit the influence of the player on actual outcomes and narrows the scope of play in general.

Couldn't agree more with that. Strategic difficulty should have a lot to do with a player's success in a game.

Quote from: jhkim;688268Challenge to the players doesn't come from chance of failed rolls - it comes from consequences of their decisions.

Totally agreed on this.  The presence of interesting decisions is really the critical piece of design, not the percentage chance of success.

From a Game Theory (math, not Forge, put down the pitchforks) viewpoint, randomization can help keep things interesting in the case of sequential, perfect-knowledge games (which RPGs tend to drift towards, but aren't inherently).

I think the other thing is understanding which types of decisions you want to emphasize in the game - is it about bonus stacking to minimize the chance of failure?  Resource utilization?  Handling the results of failure?  Charop to reduce chances of failure?  I think those are generally all things you need to know before you figure out your success percentages.

Quote from: Doccit;687650What does margin of player growth mean exactly here? When you level up, your numbers get bigger, but so do the challenges. If you can jump further and hit harder, you need bigger cliffs and things that can hit harder back. Scaling is fine as long as the thematic difficulty is scaling as well. Why would the challenges get easier as players levelled? The challenges should be advancing with them.

You may be working on the same assumption as the OP. I'd say it depends on circumstances. Does the whole less elite world simply vanish just because one character has attained some degree of experience? That would not work at all in early RPGs (in which PCs might be of widely different experience levels), nor will it satisfy those who demand some verisimilitude.

Moreover, it won't satisfy those who want advancement to show a real effect -- being able to do things easily that once were hard -- instead of just inflating numbers.

I let the dice decide how often the characters succeed (or the players decide themselves by taking approaches that don't require rolls). Sometimes they have very successful games, sometimes failure. Either way though, I've never reall seen that to be indicative of how entertaining my players find the game. As long as they aren't pixel bashing or find extended contests whiffs, I haven't noticed that success is the primary indicator of "fun" for the peoria I've played with. Emtertaining NPCs, intriguing mysteries, and unique local descriptions I would place higher in importance.