Converting a % system to a 1-20 system

[Nikoli]

Hi,

 

Warlock! from Fire Ruby Designs has a D20 system, specifically designed to play The Enemy Within. It might be what you are looking for.

But converting a D100 to a D20 won’t really change the basic probabilities; it will just reduce granularity. So the whiff factor will remain, whether 64% or 12 out of 20. (64% is quite high in WFRP. As is 50+.) 

I personally really like D100, and think Openquest or Magic World can do WFRP very well. If I ever play in the Old World again, as I hope to, I would use either MW or OQ, or a mix of both (because OQ can do cults). My one issue with OQ is it doesn’t really distinguish a warrior from a scholar in terms of how many points are distributed to combat skills. So I might change the 50/50/50 distribution to 70/40/40 or 70/50/30 (with 75 to practical remaining). That way there is less equality of skills in certain categories. A warrior would then put 70 in combat, 50 in reactions (or resistances?), 30 in knowledge. I’d use personal magic as heroic feats and/or allow them to spent as 6 growth points. As heroic feats, I imagine they might need instant activation, and not a turn as per regular magic.

But check out Warlock! It’s basically what you are seemingly looking for. D20 from a D100 system. The compendiums add a lot of other options. There’s also another book of careers. It specifically models the WFRP career system.

Edited February 13, 2022 by Nikoli
Adjusted the numbers.

[Nakana]

My conversion for d% to d20 skills is:

(% Skill - 50)/5 round down = modifier

d20 roll = d20 + modifier 

so a skill of 70% = +4 modifier

d20+4 (roll high) against DC

¯\_(ツ)_/¯ 

combat is tricky because armor absorption vs armor class doesn’t translate well so just calculate AC based on whatever dnd edition you like 

[Mugen]

5 hours ago, Nakana said:

My conversion for d% to d20 skills is:

(% Skill - 50)/5 round down = modifier

d20 roll = d20 + modifier 

so a skill of 70% = +4 modifier

d20+4 (roll high) against DC

¯\_(ツ)_/¯ 

combat is tricky because armor absorption vs armor class doesn’t translate well so just calculate AC based on whatever dnd edition you like 

That's one way of doing it, but one that gives a majority of negative skills. D&D skills rarely go below 0, except if your modifier is negative.

I'd rather use a value that can be identified as a "complete newbie" as the 0, something between 15 and 25.

Edited March 29, 2022 by Mugen

[Nakana]

4 hours ago, Mugen said:

That's one way of doing it, but one that gives a majority of negative skills. D&D skills rarely go below 0, except if your modifier is negative.

I'd rather use a value that can be identified as a "complete newbie" as the 0, something between 15 and 25.

If I’m understanding you correctly (referring to skills less than 50%) I would simply not have modifiers rather than having negative modifiers. So it would just be a d20 roll. 
 

I also know that I’m playing fast and loose with the conversion, but after all these years of playing I prefer to keep the crunch loose rather than getting bogged down by it. 

[Atgxtg]

4 hours ago, Mugen said:

That's one way of doing it, but one that gives a majority of negative skills. D&D skills rarely go below 0, except if your modifier is negative.

I'd rather use a value that can be identified as a "complete newbie" as the 0, something between 15 and 25.

I agree. One big difference between d100/RQ based RPGS and D20/D&D based RPGs is the relative competence of starting characters. In d100 games skills default at somewhere from 0 to 25% or so, depending on skill. In D20 games the default success chance is about 55% (DC10). For example to hit someone in combat requires a roll equal of greater than the target's Armor Class with the default being AC10. Giving someone a negative skill rating in D20 would essentially make them less skilled than a starting D&D character. 

IMO, a truer conversion between the game systems would probably ignore d100 skills below 50% or just pin them at rank 1 to show that the character has those skills. For combat you could average the combat skills (over 50%) to get an equivalent Base Attack Bonus in d20.  For example a character in d100 with Sword 75%, Bow 60% would have an average combat skill of 67.5% which would convert to a BAB of +4, which in turn could help in determining the character's level in D20. 

 

 

[Mugen]

39 minutes ago, Nakana said:

If I’m understanding you correctly (referring to skills less than 50%) I would simply not have modifiers rather than having negative modifiers. So it would just be a d20 roll. 
 

I also know that I’m playing fast and loose with the conversion, but after all these years of playing I prefer to keep the crunch loose rather than getting bogged down by it. 

No, not at all.

I'm just suggesting that I would rather do (skill-20)/5 rather than (skill-50)/5, just to have fewer negative skills.

When I wrote "modifier", I meant "ability modifier".

[Mugen]

1 minute ago, Atgxtg said:

I agree. One big difference between d100/RQ based RPGS and D20/D&D based RPGs is the relative competence of starting characters. In d100 games skills default at somewhere from 0 to 25% or so, depending on skill. In D20 games the default success chance is about 55% (DC10). For example to hit someone in combat requires a roll equal of greater than the target's Armor Class with the default being AC10. Giving someone a negative skill rating in D20 would essentially make them less skilled than a starting D&D character. 

IMO, a truer conversion between the game systems would probably ignore d100 skills below 50% or just pin them at rank 1 to show that the character has those skills. For combat you could average the combat skills (over 50%) to get an equivalent Base Attack Bonus in d20.  For example a character in d100 with Sword 75%, Bow 60% would have an average combat skill of 67.5% which would convert to a BAB of +4, which in turn could help in determining the character's level in D20. 

Abilities also usually have a greater impact on skills in "modern" D&D.

A typical D&D character is likely to have 16+ in one ore more abilities, resulting in  +15 percent (or more) success chance in skills related to these abilities.

In BRP related games, it's very rare to get more than 10 percent from high characteristics.

[Atgxtg]

5 minutes ago, Mugen said:

Abilities also usually have a greater impact on skills in "modern" D&D.

A typical D&D character is likely to have 16+ in one ore more abilities, resulting in  +15 percent (or more) success chance in skills related to these abilities.

In BRP related games, it's very rare to get more than 10 percent from high characteristics.

Yup.

D20/D&D works on the concept of the character having fairly good success chances for most things, especially as they increase in level. A 20th level character with a good DEX is going to end up a decent horseman by default. 

d100/RQ works on a much lower success chance, with higher success chances requiring effort and experience in the specific skill. A master swordsman with an 18 DEX isn't automatically a decent equestrian. 

 

To some extent these are design choices and converting a character from one system to the other is going to alter how the character works in gameplay, even if you have a good conversion method. For example, an 18 STR does a lot more for you in D&D than it does in RQ, and does even less for those playing Call of Cthulhu.. That's just something that doesn't translate from one game system to the other. 

[Nakana]

2 hours ago, Mugen said:

No, not at all.

I'm just suggesting that I would rather do (skill-20)/5 rather than (skill-50)/5, just to have fewer negative skills.

When I wrote "modifier", I meant "ability modifier".

Gotcha. Because of the Resistance table I view 50 as the equal point. So 50 = 0; 60 = +2; 40 = -2; etc. 

[Jim Rickel]

I will comment on something I have been working only because I am seeing some of the influences Hero Wars and I have something at ends up a bit like AGE.   I haven't looked over the file in some time, I am sure it has tons of mistakes and may be asinine.  I was working on it some time ago for friends but figure meh, I can only make a fool of myself.

 

 

Game Rules Columned .pdf

[Lloyd Dupont]

side note, I am quite impressed by the Fallout RPG (it's a 2D20 variant), haven't played it yet...

while it has no class per se and being skill and perk based. it has level (though one can be level 1 and have a few skill maxed out already)