2d6 to 3d6 (math help)

[Toadmaster]

I've been fooling around with Behind Enemy Lines, its a quick fun game but it is a tad too wargamy since there is little development of characters. I was thinking about adding to it a bit (not too much because I want to keep the quick and simple feel to it). It uses 2d6 for most task resolution, I was thinking that by using 3d6 instead it would open up the skill ranges and allow me to borrow a few bits from HERO to flesh out characters more.

 

Any thoughts on how I can bump this from 2d6 to 3d6?

 

Many of the skills have maximum levels, most range from 3-6, what would these be in 3d6?

 

How would a +1 change etc.

 

Math is not my best friend so any help would be appreciated.

 

Thanks

[Flames]

Re: 2d6 to 3d6 (math help)

 

I suggest grabbing that Excel file in the free stuff area of the Hero site that shows percentage probabilities for die roll results based on number of dice. (I think that's what it does, anyway)

 

Compare the results...

[Edsel]

Re: 2d6 to 3d6 (math help)

 

FASA's old Behind Enemy Lines is an excellent little game I still have a copy of it. I think that I may have done some work with it once. Something along the lines of what you are talking about. I will have to look over my archived files when I get home to see if I kept any of it.

[Flames]

Re: 2d6 to 3d6 (math help)

 

The Excel file is in the Character Sheets and Hex Maps area of the Hero Games website.

 

There's a page here with a chart showing the probabilities on a 3d6 roll vs a d20 roll, while this page has a lovely image of the actual curve on 3d6.

[Flames]

Re: 2d6 to 3d6 (math help)

 

Any thoughts on how I can bump this from 2d6 to 3d6?

 

Many of the skills have maximum levels, most range from 3-6, what would these be in 3d6?

I'm not familiar with that game. When you say "3-6," do you mean that the player rolls his skill level or less on 2d6 to succeed?

 

I seem to recall that Car Wars was like that.

 

Maybe we can draw up a chart that will convert a 2d6 skill roll to the nearest equivalent 3d6 roll.

[prestidigitator]

Re: 2d6 to 3d6 (math help)

 

The standard deviation of 3d6 divided by the standard deviation of 2d6 is sqrt(3/2), or about 1.2. In general to preserve roughly the same probabilities you can adjust all values to be the same distance from the mean as a fraction of the standard deviation. That means to convert a roll of 9- on 2d6 you would subtract 7 and multiply by (roughly) 1.2, then add 10.5, which comes to about 10.5+1.2*(9-7)=12.9, or about a 13-. To convert a 3-, you would do the same: 10.5+1.2*(3-7)=5.7 or about 6-. For bonuses and penalties, simply multiply by 1.2 (so a bonus of +5 becomes 1.2*5=+6).

[Edsel]

Re: 2d6 to 3d6 (math help)

 

Attached is a re-working of the firing charts that I did. I replaced the 2d6 to hit dice with a 3d6 system to grant more flexibility with combat modifiers. It doesn't have anything to do with skills though.

[Toadmaster]

Re: 2d6 to 3d6 (math help)

 

The standard deviation of 3d6 divided by the standard deviation of 2d6 is sqrt(3/2)' date=' or about 1.2. In general to preserve [i']roughly[/i] the same probabilities you can adjust all values to be the same distance from the mean as a fraction of the standard deviation. That means to convert a roll of 9- on 2d6 you would subtract 7 and multiply by (roughly) 1.2, then add 10.5, which comes to about 10.5+1.2*(9-7)=12.9, or about a 13-. To convert a 3-, you would do the same: 10.5+1.2*(3-7)=5.7 or about 6-. For bonuses and penalties, simply multiply by 1.2 (so a bonus of +5 becomes 1.2*5=+6).

 

OW, this hurt my head, I'm not sure if its what you wrote of the fact I think I understand it.

 

Thanks

 

 

Edsel, that chart may be helpful, BEL is a great game for a quick simple WW2 game, I actually have been able to round up most of the printed material for both the FASA version and the Companions version. BEL also spawned Delta Force from Task Force Games, if you like FASA's BEL you might be interested in DF, its kind of an advanced BEL set in more modern times.

 

Like most quick simple games it has some things that annoy me by going too far to the simple, like the armored combat, a hit will kill all tanks except for a Panther or a Tiger, they have a chart to show what got damaged, but that was an easy fix, I use the chart with all armored vehicles, Panthers and Tigers are tough enough without getting special treatment. But overall I think it is one of the best games for a grunt military RPG, GURPS or HERO characters are far to complex to allow the characters to get killed off in a freak occurance so there is little real sense of danger to the characters, while BEL gives some advantage to PC's to allow them better odds of surviving vs an NPC the chance of losing a PC is still quite real.

 

Flames, yes, most skills have a maximum of 3-6 meaning you have to roll under that plus any modifiers. In some ways it is similar to Carwars but more expanded. Thanks for pointing out the free stuff, I always forget to check that area out.