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design_archive:dice_rationale [2025/06/22 16:07] – created Ron Helwigdesign_archive:dice_rationale [2025/07/19 17:11] (current) – Ron Helwig
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 ### Core Concept ### Core Concept
  
-Roll a number of **d4s** equal to:+If we were to simply change from using a single D20 to using a number of D4s we could roll a number of **D4s** equal to:
  
 - **Attribute modifier**   - **Attribute modifier**  
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 - Subtract target’s **Evasion or DC** - Subtract target’s **Evasion or DC**
 - The remainder is damage (or effect strength) - The remainder is damage (or effect strength)
 +
 +<WRAP></WRAP>
  
 > Example:   > Example:  
 > A fighter with +3 STR and +2 Proficiency uses a longsword (d8).   > A fighter with +3 STR and +2 Proficiency uses a longsword (d8).  
 > They roll **5d4 + 1d8**, subtract the target’s Evasion, and apply any remaining value as damage. > They roll **5d4 + 1d8**, subtract the target’s Evasion, and apply any remaining value as damage.
 +> <WRAP notice>Note that the max roll of 5d4 is 20, simulating a D20 roll but with a smooth bell curve.</WRAP>
  
 ## Built-In Action Economy ## Built-In Action Economy
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 1. **Start of round**: Action Load = 0   1. **Start of round**: Action Load = 0  
 2. **Take action**: Add 1 to Action Load   2. **Take action**: Add 1 to Action Load  
-3. **Dice pool for next action** = Aspect value − Action Load+3. **Dice pool for next action** = Normal total dice − Action Load 
 + 
 +<WRAP></WRAP>
  
 > This replaces D&D’s Action/Bonus/Reaction system with something **more fluid but self-limiting**. > This replaces D&D’s Action/Bonus/Reaction system with something **more fluid but self-limiting**.
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 Modeled as adding or removing d4s: Modeled as adding or removing d4s:
  
-- **Advantage**: Add a d4, remove the *lowest* +- **Advantage**: Add a d4, remove the *lowest* die rolled 
-- **Disadvantage**: Add a d4, remove the *highest*+- **Disadvantage**: Add a d4, remove the *highest* die rolled
  
 Multiple stacks add/remove more dice. It’s a smooth mechanic that stacks intuitively. Multiple stacks add/remove more dice. It’s a smooth mechanic that stacks intuitively.
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 ## Additional Notes ## Additional Notes
  
-- High-tier abilities can require a **minimum pool** (e.g., Fireball needs 6 dice to cast)+- High-tier abilities can require a **minimum pool** (e.g., "Fireball needs 6 dice to cast")
 - Dice serve both as **resolution** and **resource tracking** - Dice serve both as **resolution** and **resource tracking**
 - Everything stays visible and tactile—no hidden math - Everything stays visible and tactile—no hidden math
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 - Probability modeling: <https://anydice.com/program/3c172> - Probability modeling: <https://anydice.com/program/3c172>
  
 +## Why Not D6 Pools?
 +
 +At first glance, using a pool of D6s might seem better than a pool of D4s. The variance is greater while still being a solid bell curve of probability. But there are a few problems.
 +
 +The first is that when rolling D6s it is harder to easily total the results. Using D4s leads to [most rolls are mostly pairs adding to 5](rules:sidebar_d4_math), making addition quick and easy. That isn't true with D6 pools.
 +
 +The second is that the variance between low-skilled and high-skilled characters is too vast. Trying to determine the number of dice to roll matches up pretty well with D4s but not D6s. An example might clarify.
 +
 +<WRAP important>
 +Compare the min and max possible rolls of two different pool sizes, related to their Attribute Modifier.
 +
 +| # of Die | D4 Min | D4 Max | D6 Min | D6 Max |
 +| --- | --- | --- | --- | --- |
 +| 2 | 2 | 8 | 2 | 12 |
 +| 5 | 5 | 20 | 5 | 30 |
 +
 +You can see that when using D4s it more closely resembles the results when using a single D20. The maximum a skilled character can roll is in line with what we'd expect. But the max result for a skilled character when using D6s is much higher than we'd expect.
 +</WRAP>
 +
 +So this means we would either need to create a different method of figuring out how many dice to roll, or expand the way we calculate success/failure. Doing the latter adds the problem of converting from standard D&D sources.
 +
 +But by staying with a D4 pool we can easily calculate the number of dice while making translations from D&D sources a breeze.