Hey Everyone,

I was thinking that ICRPG could be converted to just d6s. Some rolls would be a bit complicated, but here are my ideas:

Attempt roll 1d20 => 3d6.
Not a 1 to 1 conversion but should be a good replacement. Higher targets (14+) may need to be shifted down to account for the bell curve. Make 3, 4 or 5 on the 3d6 have the same result as a “natural 1” on a d20 and a 16, 17 or 18 the same result as a “natural 20” on a d20.

Effort Rolls:
1d4 => 1d3 (on a d6 1-2 = 1, 3-4 = 2, 5-6 = 3, average = 2, 1d4 average = 2.5)
1d6 => 1d6
1d8 => 1d6+1 (average = 4.5, 1d8 average = 4.5)
1d10 => 1d6+2 (average = 5.5, 1d10 average = 5.5)
1d12 => 1d6+3 (average = 6.5, 1d12 average = 6.5)

Having the effort just be a d6+x makes the rolling simpler and quicker. If you need a full range of 1d4, 1d8, 1d10, 1d12 for the tables and such then you can use the following. Each result should have an equal probability:

Equal Probability Rolls:
1d4 => Roll a d6, re-roll 5,6
1d8 => Roll 2d6. First d6 result, keep 1-4, re-roll 5 or 6. Second d6 result: 1-3 add 0 to the first result, 4-6 add 4 to first result.
1d10 => Roll 2d6. First d6 result, keep 1-5, re-roll 6. Second d6 result: 1-3 add 0 to the first result, 4-6 add 5 to first result.
1d12 => Roll 2d6. First d6 result, keep 1-6. Second d6 result: 1-3 add 0 to the first result, 4-6 add 6 to first result.

d100: Using the “d10” above, roll the 10s digit, then roll the 1’s digit.

This is a little more complicated than I originally thought it would be. Just thought I’d throw it out there. :slight_smile:


Why don’t you simply make
1d4 => 1d6-1
That would average 2.5
Although you could roll 0 then…

indeed :wink:


It is a little more complicated if you keep the idea of two rolls. Consider the idea of one roll resolution. You roll 3d6 to take an action and do not roll separately for effort.

If you are rolling d4, then you take the lowest of the 3 dice.
If you are rolling d6, then take the middle number of the 3 dice.
If you are rolling d8, then take the highest of the 3 dice.
If you are rolling d12, then take the top 2 of the 3 dice.

You then apply your effort modifier to which ever dice you pick. This means a high attempt roll is more likely to result in a high effort result. Now, this does mean you can roll something like 1,6,6 on a basic effort action and it can be kind of a letdown. If you want to avoid this, you could also say every 6 gives you +1 effort. So, even if you roll 1,6,6 you still get 3.

On the upside, this system opens up a lot of dice pool manipulation mechanic. For example, stress dice similar to the most recent alien RPG. I am thinking they are extra d6 added to the roll and you take the top 3 dice to check vs the target, but perhaps you have to take the stress dice when calculating effort? Adrenaline can push a character beyond what is typical, but the results become more random the less calm they are.

On the downside, this kind of rolling has completely different probability distributions that I have not even thought about the implications. So use this at your own peril. It just strikes me that this type of rolling could help tell the story, but avoids the numberless narrative dice that I do not enjoy.


Yes, it’s bad enough to roll a 1. A 0 would be even more frustrating. :slight_smile:


ICRPG already has separate attempt and effort rolls so I don’t think that part is too complicated.

However, this is an interesting idea. It will definitely skew the effort averages.


Keep in mind to keep things intuitive and easy for players to grasp. Nothing like finicky maths to slow turns and tune down the immersion IMO. I’m guessing you are doing this for situations where a table doesn’t have access to the weird dice?
You will never perfectly simulate the d4-d12 range, except with finicky maths. A possible streamliner:

Free effort stat bonuses based on your calculations at character creation (not including their 4 effort elective points).
Basic(1d3): 0 (max effort roll [6] gives 4)
Weapon/tool: 0
Gun: +1
Magic/Energy: +2
Ultimate: +3 (each [6] gives +1, double [6] gives +3) (or just 2d6 - 1 on an ULTIMATE ROLL is lame!)


Here’s a few thoughts I’ve mulled around in my noggin about this stuff:

  • Blood and Snow style armor eliminates the need to convert Armor Class between the d20 to Nd6. It might be a bit fiddly though, so you have to figure out stuff like, If tracked as one hit point pool would drinking a potion technically mean your armor recovers also? If track them separately, does that make it too much math for beer and pretzels gaming? You would also need to at least once convert some things over to get an intuition for how much more survivable 1 point of armor class is and what number of armor points gets you that, and then round up to keep it simple (like nearest multiple of 5).
  • I wouldn’t get fiddly about trying to convert the basic, weapon, or magic die. If you’re going to go all in on the d6 it, go big or go home.
  • Effort can be combined into the attempt if the effort value is the attempt roll minus the target number. Meaning if you roll an 8 on 2d6 targeting 7, then the effort is 1. Each point of bonus to the attempt makes the effort’s chances go up and the total possible effort go up.
  • An extra point of STR automatically gives you an extra point of Damage on attacks, so it doesn’t make sense to boost the Weapon Effort during character creation. Ditch the false choice.
  • You can still have stuff that only changes the effort, so that if you roll an 8 over a target of 7 with +1 to effort only, the result is 2. Perfect for distinguishing magic and non-magic items.
  • Explodes/Criticals would be insane. Roll a natural 12 on 2d6 attempt, and add an extra effort dice for the critical explode and then add the bonus effort after looks like this: https://anydice.com/program/20a0f
  • Abilities might need to make a school-yard trade. Not that d6s necessitate this, but if you removed Weapon Effort and Basic Effort as places to put your points during character creation, then there will be places that are meta-optimal choices (i.e. DEX is a God Stat) and that makes some character types your B rank, and that’s no fun.

Hope this gave you a gem or two you’d like to pilfer.


Yeah, my thought was the case where you didn’t have polyhedral dice. Also, I like the bell curve. :slight_smile:

The free effort you mention is basically what I proposed. :slight_smile:

The d4-d12 equivalent rolls are more for the GM in my mind. There are some tables in the book (like the L.O.G tables) that are designed for the polyhedral dice.

Players would mostly just use the 3d6 for Attempts and the d6 variants for effort.


Hey Inmatarian,

Thanks for the ideas! I’ll have to mull on them a bit.


I too wanted to do a D6 ICRPG…if you search it…it’s discussed in part in Conversion Blues

But some posts I reply to are deleted so it’s no longer simple to follow.

I still love dice pools and if I ever make a complete game TTRPG from scratch it’ll have D6 pools just because they are fun.

I’d probably do 3 stats, purchased abilities/powers, and a skill point per milestone.

As to ICRPG conversation.
All stat rolls start at 3d6 easy is +1 die hard is -1
Starting stat build points is 3~5 points…these add a die to the roll so depending on the power dynamics you want, 3 is fine for most games.

So let’s say our warrior has has +2 str.
Easy roll would be 6d6 for action
Normal roll would be 5d6 per action
Hard would be 4d6

Crit success would be half or more die =6…(not needed.)
Crit failure would be half or more die = 1

Damage is where I would go off the icrpg norm.
Every 4 or better is a point of damage, every 6 is 2.
If our +2 Str warrior hits with a roll of 2,3,4,5,6 she makes a Target Number of 20 and does 4 points of damage + effort type she may have.

And in keeping with the D6 theme, hearts = 6

Problem with this mechanic, Maths…need to add up the roll, and need to count up the hits. But for the most part it would play off of ICRPG sheets, but the feel is different.

Reason critical success is not needed, a roll of 2 6s with 3 dice is minimum 4 damage. And if using hearts = 6…it’s a big hit…if you add a crit die (D6 to effort) it becomes overkill. But you might want to track for progression.

Dice range = 3~18 with 10 or 11 being most likely…based off of memory. But this shifts by +3.5 as you add dice.

Now since effort is changed to based off of action roll results, have the effort mean what it is, no tools, tool, ranged, magic.

Beware +1 Str or +1dex means a lot more on equipment. + 1 effort means a bit more but not a lot.

Anyway there is something more to think on. :-p


Yea agree with Pax and inmatarian, if you’re going to go only d6 - go hard for that hawt dice pooling satisfaction!

Maybe the heavy maths can be solved by tinyRPG/MouseGuard approach of counting 5/6 as successes. TN = number of successes needed.

Maybe this is too far from ICRPG though. Up to you, innit.

You could even count 3/4s as partial success if you want to chuck in some DungeonWorld as well xD (ok I’m loosing control. RESPECT BOUNDARIES?!???)


High TNs like 24 can equal the satisfaction…also mechanically force players to specialize their characters.

Where it gets interesting is with TN 18…allowing only extra effort to equal damage. So after a TN of 18 any extra dice do damage straight.

So if I have 4d6 for STR. And I roll a 3 a 4 a 5 and a 6 = 18 no damage. But a 5,5,6,6 is = 4 damage. And you can say a pole arm is -1d6 but +2 dam and armor…things get downright strategic.

Making magic ignore armor or -6 TN but cost 2 HP per dice rolled…things get interesting for players…when to use magic?

Spells in this should have a max per target HP amount so 1 Target =6 but 2 targets = 4, 4 targets = 3, 6 targets =1. But effects can be added…6 targets with sleep vs 1 Target obliterated???

In reality there is a lot of choices in this space and it is up to the creator to negotiate it.


I don’t think you really need to do anything funky with the effort dice. Between a d6 and a d8, the difference is not huge, you could easily have weapon and magical efforts both use a d6, even the basic effort could be a d6, depending on how you run your games. The ultimate effort die can easily be 2d6. If you run with the gunpowder effort, you only have to choose how the d10 is converted, either 1d6 with powerful bonuses like double damage or 2d6 with tuned down additionnal effects.

Having attributes much higher than the average might be an issue balance-wise, you might want to limit how much PCs can invest in a single attribute at character creation. Also, to compensate for how stronger a good defence became, you might want to find an easy way to score a guaranteed hit, IE a double 6 (roughly 1/14) is a critical hit. Easy and hard checks can simply be a 4d6 roll droping either the lowest or the highest.


I came up with these rules for my shadowrun games a few years ago…


Each point in a STAT or EFFORT grants 1d6 to roll in a pool. i.e. STR +3 = 3d6.

  • STAT and EFFORT CHECKS succeed on a 5 or 6.
  • The ROOM TARGET determines the number of successes needed. Typically 1-5 Successes based on the highest enemies HEARTS.
  • If you roll enough successes to meet or beat the TARGET, your task succeeds and you roll for EFFORT.
  • Most Loot and Ability Bonuses convert every +1 = 1 dice bonus to rolls. I.E. +2 Sword = 2d6 dice bonus to STR dice roll. STR +3 = 3d6, Player rolls 5d6 dice pool.

Effort is rolled the same as a STAT CHECK… 1 point of EFFORT grants 1d6.
For each 5 or 6 rolled, you create 1 point of EFFORT/DMG.

Playtest Notes

  • You always roll at least one die no matter how many penalties you incur.
  • If your ABILITY points are zero, roll only 1 die.
  • If your EFFORT points are zero, roll only 1 die.
  • Easy rule grants 3 bonus dice (dice or successes, GM’s choice).
  • Hard rule removes 3 dice. (dice or successes, GM’s choice).


I play a mostly d6 game (Blood & Snow) with my kids. We have bags of polyhedral dice, but I find the game moves a lot faster and smoother if you know you are going to be rolling the same dice.
The one thing we do differently is we keep the d20, so technically it’s a d20 & d6 system.
Anytime someone would roll a for basic, weapon, or any other kind of effort, they use a d6. We don’t do any wonky math.
If we were to use magic, to not lose its punch, it would avoid armor. We use the Blood & Snow version of Armor.

We have also tried this:
Roll n number of d6 where n equals the die value. ie. d8=8
If a player were to normally roll a d10 then they roll 10 d6.
4-6 is successful.

We have even played around with AC in this way. An armored dragon might only get hit by sixes.

I have found that my kids like the d20, so they wouldn’t want to lose it. The other dice? They are cool at first and then it just becomes a hassle to manage. IMO


have you guys looked at the d6 pool of games from Free League.

you take so many d6 that you have in attribute and loot bonus. Roll and check success.

Example, Strength +3, Iron gloves +1 Str.
You get 4 d6 to throw.

1 is fail
6 is success

in a fight, each success is damage.

I was looking into the dice Pool for ICRPG, but in the end dumped the idea for the love of the d20.

Forbidden Lands, Alien RPG and Mutant year Zero use the dice pool

what I did like was the punishing system for fail throws and the push your luck mechanics


check it out, it is a good read


I’ve taken on a similar task of converting ICRPG to a D20/D6 system.

This what I’ve hacked, but there is still some work to be done.

There are the basic stats: strength, dex…
Then there are the two effort dice: magic effort and weapon effort.

I’ve dropped things like gun effort and all that stuff.
If you have a more powerful weapon, like a magic sword, there is a flat damage increase put on it. For example, a magic arrow might have +1 weapon effort.

Things like picking locks or moving boulders are based on a number of successes.
“That lock needs two successes. It’s a dex or whatever roll to unlock it, if you hit the TN then you have one success on it.”

If a player has a skill or loot that gives them proficiency, then they can roll with advantage like in 5e, except if both rolls are a success, it counts as two successes.

“That lock needs two successes. It’s a dex or whatever roll to unlock it, if you hit the TN then you have one success on it.”
“I have a lock-pick kit.”
“Good. Roll two d20.”

Magic effort does not act as a modifier to the cast like this spell does this damage +magic effort.
Spells are leveled by hearts and cast over multiple turns.

For example, a level one spell is one heart. This means that the player would say that want to cast the spell and roll a d20 and d6. If the d20+modifier hits the TN, then you add the d6 roll with the magic effort, let’s say the d6 is a 3 and the magic effort is a +1, then they have 4/10 of the spell prepared. Then can continue to cast this spell on the next turn.

A failure doesn’t stop the spell unless it’s a natural one. A failure just doesn’t contribute to casting the spell. Taking damage and other things in the environment can make a spell roll hard (+3 TN). Once the spell is cast, it goes off. This allows magic to be powerful but at a cost of turns.


No. Just No.
ICRPG is almost perfect as it is. Hack it a little = better game for you. Hack it a lot = ruin it.

“so let it be written. So let it be done”
– Ramses II (played by the great Yule Brenner)


ICRPG is perfect as is, but my kids just don’t get it. Too many different dice. They struggled with 5e for the same reason.
I don’t know what it is. My father gets tripped up with it too. I would give my kids time to get an (8) is gun effort and blah blah, but my dad isn’t the kind of old dog that learns new tricks.
So, I’ve had to make modifications, because I dig ICRPG and don’t know anything else besides 5e.
Any suggestions?


There’s a game called “Whitebox: Fantastic Medieval Adventure Game” that’s a very simplistic take on the original D&D materials. In terms of making an ICRPG that’s just the d20 and the d6, I would look there for possible inspiration. The PDF is free on DTRPG.