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The effects of using 2d6 in Unisystem instead of d10

Wolfspider

IDEA!
Validated User
I have heard several people say that they prefer to use 2d6 instead of 1d10 for Unisystem.

I admit I know very little about probabilities and such. I have heard that the d10 is a bad die to use in a game, but I don't really know why.

What would be the practical effects of using 2d6 instead of 1d10 in Unisystem? Would those of you who understand probability and such recommend such a change? Why or why not?

Thanks.
 

Rich H

Owl Be Back!
RPGnet Member
Validated User
With a d10 you're equally as likely to roll a 1 as you are a 10. So the dice give the game a lot of unpredictability and a range of results all just as likely to come up as another.

Rolling a 2d6, the most likely result is a 7. This is followed by 6 and 8, then 5 and 9, then 4 and 10, then 3 and 11. And the extremes (rolling 2 or 12) are even less likely. So as you can predict the dice roll its easier to predict results and therefore build the right difficulty levels on target numbers for your game.

When I ran Unisystem, I used 2d6 rather than 1d10 but I also tweaked the game's difficulty target numbers.

It all depends on how you want to play your game though, really.
 

DrFaust

Roll away the dew.
Validated User
What would be the practical effects of using 2d6 instead of 1d10 in Unisystem? Would those of you who understand probability and such recommend such a change? Why or why not?
Random Code said pretty much everything I was, but I will also point out you would probably need to alter the exploding dice rules, since the written version requires a second roll to check to see if they continue to explode, IIRC.
 

Harwel

¯(°_o)/¯
Random Code said pretty much everything I was, but I will also point out you would probably need to alter the exploding dice rules, since the written version requires a second roll to check to see if they continue to explode, IIRC.
Just give them a 50% of adding/subtracting another 1d6 if you roll box cars / snake eyes. That assumes you're playing Classic Uni, Cinematic doesn't have exploding dice in the RAW.
 

Wolfspider

IDEA!
Validated User
With a d10 you're equally as likely to roll a 1 as you are a 10. So the dice give the game a lot of unpredictability and a range of results all just as likely to come up as another.

Rolling a 2d6, the most likely result is a 7. This is followed by 6 and 8, then 5 and 9, then 4 and 10, then 3 and 11. And the extremes (rolling 2 or 12) are even less likely. So as you can predict the dice roll its easier to predict results and therefore build the right difficulty levels on target numbers for your game.

When I ran Unisystem, I used 2d6 rather than 1d10 but I also tweaked the game's difficulty target numbers.

It all depends on how you want to play your game though, really.
Thanks for the explanation. Now I understand the issue better.

Could you post your tweaked difficulty numbers? Did you also modify the Success Levels table?
 

Rich H

Owl Be Back!
RPGnet Member
Validated User
Thanks for the explanation. Now I understand the issue better.
No problem, I'm glad it made sense!

Could you post your tweaked difficulty numbers? Did you also modify the Success Levels table?
Its so long ago that I just made rough notes and never kept them, sorry. I don't think I modified the degrees of success though, just the target numbers for the difficulty of tasks.

I didn't convert the exploding dice roll - ie, the 'if you roll a 10 then roll again' type rule, though.
 

Harwel

¯(°_o)/¯
I'm at work, and don't have any games here, but doesn't every Unisystem game provide optional rules for 2d6? I think they recommend 2d6-1, which is effectively the same as rolling 2d6 and increasing the TN by 1. It might be 2d6-2, I can't remember offhand.
 
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Rich H

Owl Be Back!
RPGnet Member
Validated User
I'm at work, and don't have any games here, but doesn't every Unisystem game provide optional rules for 2d6? I think they recommend 2d6-1, which is effectively the same as rolling 2d6 and increasing the TN by 1.
Dunno, mate. I don't have any Unisystem books any more. I do remember that my alteration to the target numbers was very small, just one or two points, and I do think I increased them so what you say does hold water.
 

Wolfspider

IDEA!
Validated User
I'm at work, and don't have any games here, but doesn't every Unisystem game provide optional rules for 2d6? I think they recommend 2d6-1, which is effectively the same as rolling 2d6 and increasing the TN by 1. It might be 2d6-2, I can't remember offhand.
I don't remember reading about this optional rule in any of the Cinematic Unisystem rulebooks I have (which is all of them).

Perhaps it is in one of the AFMBE books....
 

Harwel

¯(°_o)/¯
I don't remember reading about this optional rule in any of the Cinematic Unisystem rulebooks I have (which is all of them).

Perhaps it is in one of the AFMBE books....
I think it might be AFMBE. I just downloaded Witchcraft real quick just for giggles and it makes a passing mention that six siders can sub for d10 but doesn't go past that, at least not that I could find quickly. I can look when I get home. Either way, increasing the TN by 1 (or 2d6-1) might make things slightly easier than 1d10 on average, and increasing by 2 (or 2d6-2) will make things slightly harder. So you can tweak that to taste for what you want for your campaign, really.

(Logic: the average roll on 1d10 is 5.5, and the average roll on 2d6 is 7, so the difference is 1.5. Round that .5 however you want.)
 
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