I must create a system, or be enslaved by another man's. I will not reason and compare: my business is to create.

- William Blake

Thursday, June 01, 2023

d100 skills for B/X and AD&D

One thing that drives me crazy about old school D&D is how random skills checks are - to the point of the same character having two different methods of making the same check (e.g., B/X Halflings having 90% chance when hiding in the wild and 2-in-6 elsewhere).

Lamentations just uses 1d6 for most checks, while Dark Fantasy Basic uses only the d20. Labyrinth Lord uses the d100 for all thief skills, but other methods for other checks. 

I like the d100 - could we use that for everything?

Let's try to convert existing checks to a d100... while keeping vaguely similar chances.

Ability checks - just use 5% per point for ordinary tasks. Strength 12 means you succeed 60% of the time. Multiply the stat by a different number if the task is too hard or too easy. For example:
- 1% for the nearly impossible (e.g., bend bars, identify potions and magical items without trying them).
- 2% when the game says you have a 1-in-6 chance (should be 1.5% but let's keep it simple).
- 3% when the game says you have a 2-in-6 chance.

Saving throws - 20% plus a level bonus. You can use 5% for everyone but 3/4/5 (or 2/3/4 in B/X) for mages/others/fighters is even better. Demihumans add 20% or something.

Thief skills - 2% per ability point for everyone, but thieves also add 5% per level. 

Turn Undead - 50%, plus 10% per cleric level, minus 10% per undead HD. 

Attacking - 3/4/5 per level for mages/others/fighters (or 2/3/4), plus 1% per point of Str (melee) or Dex (ranged). Armor reduces this by 5% per point of armor (10% for leather, 20% for chain, etc.).

Open doors - use ability checks (Str). 

Reaction rolls - use ability checks (Cha) to change reaction by one step. Cha no longer affects reaction rolls

Survive Resurrection/ Raise Dead/System Shock - 20% plus 5% per point of Con.

Magic - Int/Wis check (1%), plus 5% per mage level (3% for clerics, etc.). You need at least 10% to cast 1st-level spells, 20% for second-level, etc.

But why?

There are certain things we can do with a d100 that are harder to do with a d20.

- A "35% chance" or similar is always very intuitive to anyone.

- Critical hits and fumbles when you roll doubles (11, 22, 33, etc.). If a thief fails to disarm a trap, he only gets hurt 10% of the time. Likewise for climbing and falling, etc. In combat, a critical hit can either double damage, ignore armor, give you a free attack, or something else.

- Ability scores: each point matters! I love that!

- An easy solution (1%) for very hard tasks.

- Great granularity, you can play endlessly with 1% increments. You could even add 1% per level to ALL adventuring checks that are normally unaffected by levels, as PCs should get better at not getting lost, etc.

Would I use this?

Not really - it is still too fiddly for my tastes. Unless you use a spreadsheet to calculate these things automatically. Maybe it could work with a bit more streamlining... Maybe letting PCs assign a number of points to combat, skills and magic (and HP) per level... But we already have Runequest (or Mythras) for that. 

These are fine systems, BTW. But I guess I'm sticking with the d20 (and my minimalist OSR game) for now.

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