Check my math?

[Leitz]

If you roll 2d10, there are 100 possible combinations. If I understand correctly, here are the possible rolls, and the frequency of each two dice combination.

Code: Select all

2:   1
3:   2
4:   3
5:   4
6:   5
7:   6
8:   7
9:   8
10:  9
11: 10
12:  9
13:  8
14:  7
15:  6
16:  5
17:  4
18:  3
19:  2
20:  1

If that's correct, then there's a 10% chance of rolling exactly an 11, a 28% chance of rolling between 10-12, a 44% chance of 9-13, and a 58% chance of 8-14.

And if that's correct, then a +1 or +2 becomes very significant, unless you roll like Rex.

Correct? Or am I missing something?

[sastaz]

You are correct

Maybe that's how you did it, but I find it easiest to think about it in combinations. Let's say you roll the red and blue d10. There's exactly one way of rolling 20 (both 10). Two ways of rolling 19 (red 10 blue 9, and red 9 and blue 10). Three ways of rolling 18 (10+8, 8+10 or 9+9).

So out of 100 different combinations, there are three that leads to 18 and chances of that happening is 3 out of 100, or 3/100 = 3%.

Rolling 11 is the "easiest" with most combos making that happen (1+10, 2+9, 3+8...)

It becomes a bell curve.

Rolling 10-11 is simply a matter of adding all outcomes that make 10 with all of those that make 11 and then divide by 100.

[sastaz]

Fun fact is that the 3d6 bell curve is really close to actual normal distribution of traits in humans.

[Rex]

Math looks good Leitz. Here is a good program to use for dice probabilities. Interestingly I played in a D&D game once where we used 2d10 instead of 1d20 rolls. Changes the feel of the game a bunch.

https://www.anydice.com/

As far as a normal distribution, 3d6 is that. Patterns in nature tend to be normal distribution (tend but not always). But not necessarily exactly the same as 3d6 for example. IQ is an easy example, it is a true normal distribution but not even close to the same scale as 3d6. An 18 on 3d6 occurs 1 in 216 times. So a max Int for D&D is relatively common. My little town of 1900 people would have 8 or 9 people with an 18 Int. But the Stanford-Binet IQ test has an IQ of 145-160 as very gifted or highly advanced (the max is 160 on this scale). A 160 S-B IQ occurs 1 in 11,307 people. To be clear here, I am not implying that Int = IQ, just using it as an example we have good understanding of the distribution of in humans.

[Leitz]

Interestingly I played in a D&D game once where we used 2d10 instead of 1d20 rolls. Changes the feel of the game a bunch.

That's where I'm going with this; doing a non-Old School retro clone that gets rid of a lot of charts, and where modifiers mean more. Still in the very rough stage (thoughts on post-it notes), and it needs a lot of thinking through.

[Rex]

It will work. We found that really good armor classes could become very difficult to hit for low level characters so I would recommend making some of the better armors much more expensive. From a historical standpoint that is needed anyway since armor and weapons in D&D are both very cheap compared to historical.

[Leitz]

Right now I'm taking a totally different tack; armor just absorbs damage. Here's an example:

Fred wins initiative, and swings Guido. Both roll 2d10 and add/subtract modifiers. If Fred ties or wins the roll, he does the difference, plus weapon damage (1d6 for 1 handed weapons, 2d6 for 2 handed). Guido's armor absorbs some of the damage, and he takes the rest.

Thus a highly armored character with some skill may be "hit" a lot, but take little damage. If you're an unskilled fighter in cloth armor facing a renowned knight with a two handed sword, running away is a viable option.

[Rex]

Sounds good. HarnMaster uses a similar system for armor. Going a step further it protects different depending on the type of armor and the type of attack (blunt/edge/point/fire)

[Leitz]

Sounds good. HarnMaster uses a similar system for armor. Going a step further it protects different depending on the type of armor and the type of attack (blunt/edge/point/fire)

Yeah, I'm in the "fewer tables and less crunch" camp myself. Harn has a lot of world data, and we played it a little. What was the other one, that ended in "Master"? I think it was used as the basis for Middle Earth RPG, we called it "ChartMaster". The critical hit results were fun, for a bit. Printed on nice parchment type paper, too.

Addendum RoleMaster

[Rex]

Yup, more crunch. Chart master is a nick name for Rune Master I think. Which is what HarnMaster is an off shoot from. The thing I like most about HarnMaster is that the advancement is built right into every roll. Any critical (good or bad) allows you a chance to improve, with the better you are at something the more difficult to improve you become. So the young farm boy just learning sword gets better much quicker than the veteran mercenary. But the farm boy is in serious trouble in a sword fight against the merc.

[Leitz]

First mad scribbling of rules done. No spell lists, if we do something with the ScenSim I'll probably use the AD&D spell lists. Or run it historically and just work skills and fighting. Lots of gaps to be fixed, and more to be found once we actually play it a little.

[Rex]

Sounds interesting.