"Basic roll under mechanic (d20) " Topic
13 Posts
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bpmasher | 04 Oct 2018 7:18 a.m. PST |
d20 -based roll under mechanic idea here: Stream of consciousness… Stats revolve around Combat, Social, and Spiritual (magic, confidence etc.). Max stat is 19. - You always roll under with a d20. A 20 is a fumble, a 1 is a critical success. Stats have associated skills (if you want) that have a max of the same value as the stat. Alternately, characters could choose a specialization under a stat and gain a +1 bonus towards that specialty only (Like a Combat stat of 12 with an associated martial arts specialization of +1 = 13 skill). Success ratio is apparent = 5% per point in attribute or skill. Average stat and skill is 10, which could be said to be very proficient. Firearms combat is deadly. Let's say a firearm does max 10 damage (9mm pistol) and the average Combat stat is 10. You could take someone out with one skilled shot. Melee damage is similar, but works as such: anything under 10 does it's roll value in damage (still deadly), BUT you don't get the advantage of higher skill as much because anything over 11 does the sum of the values' numbers in damage (11 becomes 1 + 1 = 2). Thus unarmed combat is more unpredictable. Weapons add +1 or 2 depending on how hefty they are. Melee combat is a contested roll-under mechanic with an attacker (the character taking an action) and a defender. You have to roll under your skill, but higher than your opponent. Tricky business, not getting hit. Combine this with the higher damage with lower rolled values, which means a "poor" defense means you get hurt more badly within the possibility of the dice. Shooting is more straightforward: Roll under your skill. A shock mechanic is easy to implement (per character). Average the value of Combat and Spiritual stats, multiply by 1.5. The resulting value is the Shock stat. Shock is dealt either with a variable multiplier modifier (1d3, 1d4) or with a flat multiplier (x3). When a character takes shock they are out of the action until they take enough "recoveries" with their Combat stat being the recovery value. Could be used for social combat as well (Mind + Spiritual stat average x1.5), like intimidation, bribery or interrogation attempts, with a success treshold mechanic (any result over the Social Shock value means it was a success). What to use this with: a board game with fluff, straight up skirmish game, light RPGs. |
Yellow Admiral | 04 Oct 2018 8:17 a.m. PST |
From a game design perspective, using 2 or 3 dice to get a bell curve makes the results more predictable and corner cases less likely to end the game early or take it into a weird situation that needs GM intervention. A single die by nature gives wild and chaotic results, and has a greater tendency to let luck dominate the narrative. As a GM, I find myself interfering more to mitigate radical swings of luck from single-die systems, and that just gets tiresome. Single die results make more sense when there are going to be a lot of them together and each has a small effect, e.g. firing a broadside or fusillade where each gun gets a die and the target can take a lot of "hits" before degrading. I would add that lot of your examples have a strong role-playing or semi-role-playing theme, which makes steadier, more predictable results even more important – any system requiring an investment of time and ego in individual characters is immensely frustrating if those characters evaporate in a fog of blood at the slightest mischance. Of course, you can always combine these ideas. For instance, divide characters/units into two categories, "heroes" and "redshirts"; heroes roll 2d10, redshirts roll 1d20. The redshirts will tend to die and die and die (and kill and kill and kill each other) while the heroes will tend to have more persistence through the game or campaign. Other than that, nothing wrong with the basic concept. I think the "roll under but beat opponent" concept (and it's reverse) is really neat, I've used that idea myself.
- Ix |
bpmasher | 04 Oct 2018 9:29 a.m. PST |
Thanks for the feedback. I will keep working on this since I've been looking for a simple solution for my gaming ideas. |
GildasFacit | 04 Oct 2018 12:41 p.m. PST |
Not so YA. This is a roll with a predictable probability (for any specific stat roll), not a selection of random possibilities. Attempting the same idea with 3d6 would still have a fixed probability of success. The only difference between the two would be the even steps up the scale with 1d20 compared to 3d6 (or any other combo of dice). Try to roll under a stat of 10 would be 36% for 2d10 & 45% for 1d20, for a stat of 11 45% for 2d10 & 50% for 1d20 and so on (they'd only be the same at 12). |
saltflats1929 | 04 Oct 2018 3:25 p.m. PST |
You are basically describing the GuRPS system, except it uses a 3d6 bell curve system to keep most rolls in the 9 to 13 range. Stats are still 1 to 20. |
Thresher01 | 04 Oct 2018 4:30 p.m. PST |
Works for me. I use that all the time. 2D10s are good too, and there is a case to be made for both, as well as percentile dice, depending upon the application. 50% chance to hit makes sense, at point-blank/short range vs. an unmoving/unevading target. Much lower though, if your target does either. Evading at PB/Close range is even more effective than at longer ranges, due to angle-off issues, and inability of the firer to adjust to that, properly. I'm also a fan of multiple D20s, with lower to-hit values – one for each shot, or for multiple shots in a burst. |
UshCha | 04 Oct 2018 8:46 p.m. PST |
The buckets of dice approach also has limitations. While the distribution about the nominal value is quite stable. Take 2 d 20 distribution for 2 die is:- score 10 or less PROBABILITY 210/400 52.5% Score 5 or less PROBABILITY 10/400 2.5% Proability 1/400 Now add a plus 1 modifier score 11 or less Proabability 229/400 57.25% Score 6 0r less Proability 15/400 3.75% Now this illustration is not for a roll under system but illustrates that the impact of a modifier is a function of the base score to which it applies. i.e plus 1 on a base score of 2 changes the odds from 0.25% to 0.55. On a base score of 10 the plus one changes resulst from 52.5% to 57.25% whereas ion a score of 5 the plus 1 changes from 2.5% to 3.75% It depends whether you want your modicfiers dependent or independant of the base score. Personally I find the multi dice system has more problems than it solves but that is a desighn issue. Where I needed a "bell cureve" type result we had a small table (below). Again its what you want. Random Die thrown D20 Score 20 UP 3 18-19 UP 2 15-17 UP 1 7-14 No shift 4-6 Down 1 2-3 Down 2 1 Down 3 |
Yellow Admiral | 04 Oct 2018 9:11 p.m. PST |
Not so YA. I'm not sure why you say "not so", and then go on to illustrate what I'm talking about. It's true a bell curve has lower probability results at the tail ends and a non-linear progression, but that just means the roll-under scores should be concentrated in the middle or upper middle end of the 1-20 range. The tail effect of a multi-die bell curve can be mitigated somewhat with interesting die mechanics. Maybe roll 2d10 counting the 0 as a 0, giving a result range of 0-18. Maybe the "roll of 1 always succeeds" rule literally means a 2d10 roll has two dice that can show a 1, massively stacking the odds in favor of 2d10 (minimum 19% chance of success). Etc. Anyway, my point was not to work out fun gimmicks to tweak the stats, but just to point out that games with single-die critical decisions have a nasty tendency to violate expected scenario bounds. A game that ends at the beginning of turn 3 because a few strategically bad die rolls blew up half the "good guys" and ran most of the rest out of ammo is no fun. Bell curves go some way to mitigate things like this. - Ix |
GildasFacit | 05 Oct 2018 6:37 a.m. PST |
YA – My comment concerned your first paragraph, particularly your claim that … "A single die by nature gives wild and chaotic results, and has a greater tendency to let luck dominate the narrative" This is simply not correct. Chaos implies a system without rules and the calculation of the probability of any value on a single die is not only simple but entirely predictable. It isn't wild but it is a 'flat' distribution with equal probability of any one outcome. In the case of rolling under a Stat value (which is what I referred to) the METHOD of rolling a value to compare to the Stat is irrelevant as the probability of rolling under the value will always be fixed. This is not a roll to determine a number of hits or similar but a 'Pass' / 'Fail' test. Single or multiple dice have no effect on how 'wild' or 'chaotic' the results are the probability of achieving a Pass is all that is important. The last point in your second post is far more a feature of good game design than the type of dice used. Fancy schemes using lots of dice are never the answer, if you want to mitigate luck then you need to find a less random decision-making system or have situational modifiers in large numbers. |
Andy ONeill | 07 Oct 2018 2:44 a.m. PST |
Feng shui uses a target number and skill number. You roll 2d6. One + and one -. Add the result to your skill and compare to target. If you roll a 6 you roll and add/subtract again. You can always fail or succeed no matter what. Your chances of rolling several sixes are of course pretty slim. |
Yellow Admiral | 16 Oct 2018 7:19 p.m. PST |
Found it! I totally lost this thread. This is simply not correct. Chaos implies a system without rules and the calculation of the probability of any value on a single die is not only simple but entirely predictable. It isn't wild but it is a 'flat' distribution with equal probability of any one outcome. We're talking past each other. You're talking about mathematics, I'm talking about the subjective experience of the gamer. So: the probability of achieving a Pass is all that is important True, but: Single or multiple dice have no effect on how 'wild' or 'chaotic' the results are Not true. Since a flat distribution weights all results equally, there is an equal chance of always-pass (1), always-fail (20), and any other particular result. Most flat-distribution result tables list a bunch of things that should be much less common, thus the events "seem" too common or likely. Most games that end like the opening scene of Rosencrantz and Guildenstern Are Dead seem to use single-die resolution for critical results. Since a bell curve bunches results in the middle of the range and provides some nicely very-low-odds results at the tails of the curve, there are more opportunities to steer the results into lower frequencies of occurrence.
The last point in your second post is far more a feature of good game design than the type of dice used. I think choices of dice type and dice mechanics are a part of good game design. Proper choice of dice mechanics can actually lend flavor to the proceedings; improper choices can make the game process needlessly painful or random. But, again, I'm talking about subjective feel from the gamer's perspective, not about statistical correlations. - Ix |
UshCha | 18 Oct 2018 1:45 a.m. PST |
YA I think its a matter of opinion. Wild end results to ma have no interest to the game. They are in effect just gambles. I don't find gampling interesting it is just various shades of risk. Wild results can't usefully catered against so to me degade the game. If a wild result takes the game out of the set on interesting games than its not a thing I would want. |
Rudysnelson | 23 Nov 2018 6:31 p.m. PST |
The use of dice is dependent on the percent of chance you are working with. D20 is a 5% per number. The only lower percent is using two d10 with being tens and the other ones. This is my preferred system back in the late 1970s when I started. Any dice system can be effective as long as the values are consistent. |
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