20+ Resolution Mechanic.

[Hicks]

Points:

1: gamers like rolling dice.

2: adding a bunch of dice together is harder than rolling one die and adding a static number.

3: finding the highest die rolled is faster than totaling multiple dice.

4: adding large (two digit) numbers together is harder and slower than adding very small (one digit) numbers to die roll.

5: gamers think the d20 is cooler than other dice.

In 20+ you roll a d20 and compare it to a static difficulty number, higher difficulty numbers denote more difficult tasks. Should your character receive a bonus to the roll, you roll an additional number of d20s equal to the bonus; the bonus number is then added to the highest rolled d20 and that number is compared to the static difficulty number needed to succeed at the roll. Bonuses are small (seriously, like +1 or +2), but more skilled characters succeed more often, achieve a greater margin of success, and have have a lower margin of failure.

What do you think?

[John Magnum]

Let me run a few quick numbers.
Say the DC is 15, so you succeed on 15, 16, 17, 18, 19, 20 (30% of the time).

Bonus of +0: Success rate 30%.
Bonus of +1: Success rate 57.5%
Bonus of +2: Success rate 78.4%
Bonus of +3: Success rate 90.8%

Not a terrible curve, I don't think. It's pretty easy to calculate the odds of success for a given DC and bonus, although it's not easy to do so on the fly. On the other hand, I don't actually know off the top of my head what the expected value of your roll is. Clearly it's 10.5 for a +0, and it's not too hard to brute force a +1, but I don't know the algebraic expression for it.

The question is what to use it for. If you do really care about margin of success, there's some work to do hashing out the EV and distribution of the positive bonuses. If all you care about is a success/fail binary, that's fine but probably not as fine as a simple 1d100 where you can literally just write down the odds of success and have that be your roll-under.

[fectin]

N is target number
B is bonus
P = ( (21-N+B)/20 ) ^ (1+B)

I think. I haven't checked.

[John Magnum]

Fairly badly off, actually. That's the probability that you beat the target number 1+B times, when you want the probability that you beat it at least once.

The expression for the basic odds of success is, using your variables

P = 1 - [(N - B - 1)/20]^(1+B)

[Korgan0]

There's going to be very little granularity, though. For a super-rules light system it might work, once you get beyond a +4 bonus you're going to pretty much always have a high die, so there'll be very little variance in rolls, so the bonus number (which you'll have to keep small) will end up being the decider. So basically, you'll have to say goodbye to small bonuses for tactical positioning or whatever, and I'm not sure that's a bad thing.

[shadzar]

What do you think?

sounds like AD&D.

roll d20, add some modifiers, check a success range of number to see if it falls within the range, otherwise it fails.

what is the point of the thread again? no, seriously.

[hyzmarca]

What do you think?

sounds like AD&D.

roll d20, add some modifiers, check a success range of number to see if it falls within the range, otherwise it fails.

what is the point of the thread again? no, seriously.

No. You roll 1+X D20s and take the highest, where X is some unspecified bonus.

Translating to 3.5, a character with a BAB of 11 would roll 12d20 and take the highest on attack rolls.

As bonuses add up, the the RNG skews high.

[CCarter]

The major issue with it is that the maximum doesn't change regardless of how many dice you roll, and its actually the most common result for most characters (where their dice pool is greater than 1).

Hence-
20s aren't very exciting
Amateurs can always accomplish very the most difficult actions, unless you also add on either bonuses from somewhere, or some sort of exploding dice roll system.

I think the lack of granularity is also going to be an issue for having both attribute and skill factor into rolls; either dice pools are going to be quite large or you end up having to use one of them (e.g. attribute) as a flat + to the roll, or have to figure out some other way of handling attributes (changing skill purchase costs, for instance).

[Stubbazubba]

I'd replace skill training with extra d20s, keep other modifiers as a + to the roll, take the best total. This way your DCs can still go up. Cap the training at 3 or 4 d20s.

[tussock]

Uh, @last 3 people, original post says +11 gives you best 1d20 (of 12d20) +11.

@OP, it's a dice pool where you're lowering the target number as you add more dice. That's probably not a good idea, in that dice pools are extremely coarse and difficult for players to understand at the table.

Also, as John Magnum showed, the bonuses are overwhelming your RNG. A d6 has more tolerance for bonuses.

[Hicks]

The idea is that somethings are actually impossible for an untrained character, like trying to roll a DC 21 or more on a single d20 but with training, ability, and circumstance (+3) the likelihood of success is greater than 15% (as it would have been with only one d20 and adding 3 to its roll).

The bonuses in 20+ are extremely tight and often conditional; everything that stacks added together is seriously like +6.

[John Magnum]

Be aware: +6 is a fucking massive bonus. With +6, you succeed on a DC 20 over 92% of the time. You succeed on DC 23 just under 75% of the time. The breakeven DC where you succeed and fail in equal measure is 25. And DC 26, the highest DC that isn't literally impossible for a +6 to beat, you still have a 25% success rate.

[Hicks]

I am aware, and the formula that you made gave the +6 bonus a 30% success rate against a DC 26, which is basically the upper limit of the system. This won't work for traditional D&D, which has you pick up 20 levels of bonuses, but it could work for something like Traveler, where you can't expect to hit a maneuvering enemy Starship 10,000km distant by leaning out the airlock and taking pot-shots with your AK-47. But with training, equipment, ability, and a stabilized laser turret you could do it while drinking a hit cup of coffee.

[codeGlaze]

something like Traveler, where you can't expect to hit a maneuvering enemy Starship 10,000km distant by leaning out the airlock and taking pot-shots with your AK-47.

I want this, nao.

[RadiantPhoenix]

something like Traveler, where you can't expect to hit a maneuvering enemy Starship 10,000km distant by leaning out the airlock and taking pot-shots with your AK-47.

I want this, nao.

How's this?

Ludicrous Shot [Combat]
Your ranged attacks hit from so far...
Benefits: This is a combat feat that scales with your Base Attack Bonus.
+0: The range increments of your attacks are doubled
+1: Your foes reduce the bonus to AC they receive from cover by half
+6: You take no penalty from range increments.
+11: You can attack from any number of range increments away.
+16: You can attack any target whose location you know. Your shots teleport to the target. Cover has no effect.

[codeGlaze]

How's this?

Ludicrous Shot [Combat]
Your ranged attacks hit from so far...
Benefits: This is a combat feat that scales with your Base Attack Bonus.
+0: The range increments of your attacks are doubled
+1: Your foes reduce the bonus to AC they receive from cover by half
+6: You take no penalty from range increments.
+11: You can attack from any number of range increments away.
+16: You can attack any target whose location you know. Your shots teleport to the target. Cover has no effect.

This deserves a munchkin award.

[ishy]

Ludicrous Shot [Combat]
Your ranged attacks hit from so far...
+16: You can attack any target whose location you know. Your shots teleport to the target. Cover has no effect.

Scry and Die takes on a new meaning.

[RadiantPhoenix]

Ludicrous Shot [Combat]
Your ranged attacks hit from so far...
+16: You can attack any target whose location you know. Your shots teleport to the target. Cover has no effect.

Scry and Die takes on a new meaning.

Hey, fighters should get nice things too, you know?

[ckafrica]

Ludicrous Shot [Combat]
Your ranged attacks hit from so far...
Benefits: This is a combat feat that scales with your Base Attack Bonus.
+0: The range increments of your attacks are doubled
+1: Your foes reduce the bonus to AC they receive from cover by half
+6: You take no penalty from range increments.
+11: You can attack from any number of range increments away.
+16: You can attack any target whose location you know. Your shots teleport to the target. Cover has no effect.

I believe the flavor quote for this should be"If only I had a bucket to put my foot in."

[RadiantPhoenix]

I believe the flavor quote for this should be"If only I had a bucket to put my foot in."

I don't get the joke.