A Skill System for AD&D
This document proposes a complete skill system inspired by and compatible with original AD&D. It is intended to be very different from the non-weapon proficiency system introduced in late-era 1st edition (OA, DSG, WSG) and carried over to 2nd edition AD&D. Notably, the philosophy is that skills are largely defined at character creation and the success rates go up with level; and that they avoid the swingy mechanic of d20 rolls compared to ability scores.
To briefly summarize: some skills are considered nearly universal and subsumed under ability checks on a d6. Everyone can attempt to be sneaky, to fast-talk a guard, to climb a tree. Opposed ability checks in this category are resolved by a mechanic similar to surprise: the base chance of success is 2 in 6 but an associated complex skill or professional training can increase the range. On the other hand, some skills (like thief skills) cannot be attempted without training. These are given a percentage rating.
Ability checks
There are many situations where the PCs need to succeed at a challenging task that anyone could attempt. The most prominent example in the rules is trying to sneak up on or ambush an enemy, which for most people will succeed 33% of the time (1-2 on a d6). But the rules have other examples: opening a stuck door, finding a simple trap, and reflexively avoiding danger are often adjudicated with a simple d6 roll in early books and modules.
We can propose a universal mechanism for such "ability checks" similar to the "Open Doors" rating of Str. Let’s call such checks “minor feats”.
Ability Score | Open Doors (for ref.) | Minor Feat | Complex Skill Bonus |
3-4 | 1 | 1 in 8 | -20% (can’t learn) |
5-7 | 1 | 1 in 6 | -10% (can’t learn) |
8-13 | 1-2 | 1-2 in 6 | No adjustment |
14-15 | 1-2 | 1-3 in 6 | +1 level |
16-17 | 1-3 | 1-3 in 6 | +2 levels |
18 | 1-3 | 1-4 in 6 | +2 levels |
18% | 1-3 to 1-5 (1 or 2 in 6) | 1-4 in 6 | +3 levels |
19 | 7 in 8 (3 in 6) | 1-5 in 6 | +3 levels |
20 | 7 in 8 (3 in 6) | 7 in 8 | +4 levels |
Note: the “complex skill bonus” only applies if bonuses/penalties are not otherwise defined in the PH, for example the thieves’ skills. The penalty only applies if the skill is a guaranteed skill for a class: e.g., clerics with low intelligence might still know Lore (Religion) but they are less likely to recall facts.
Examples of minor feats:
- Str: open a stuck door, swim against current, break out of a web, catch someone falling from a height to prevent damage, climb a tree quickly
- Dex: dodge a trap, catch a thrown missile intended to hit or break, tie a knot quickly
- Con: endurance running or forced march; hold breath > 1 minute
- Int: Copy symbols from memory, detect a simple trap or concealed door, solve a riddle, remember details of an in-game event
- Wis: Sense a magical ambiance, psychic probe, or resisted spell. Apply first aid to regain 1 hp.
- Cha: fast-talk or bluff an NPC (see below)
At the DM’s discretion, a bonus or penalty (usually just one point) can be assigned to the chance of success based on the difficulty of the feat or the PC’s background implying practice/training in the task (see professional/secondary skills). In this context,
detecting concealed doors can be considered a minor feat for Int, with a 2 in 6 base chance. A true secret door penalizes this to 1 in 6; while elven heritage provides an offsetting bonus.
Finally, I suggest that the “minor feat” roll be reserved for actions under pressure or with important story consequences; in other situations, a PC with odds better than 50% succeeds automatically.
Opposed Ability Checks
Surprise is an example of an opposed ability check, (active) stealth vs (passive) awareness. The standard rules are:
- The base chance of success (i.e., opponent is surprised) is 1-2 in 6.
- Some individuals have a professional advantage due to background or training (elves, rangers, etc.) so their base chance increases to 1-3 in 6.
- Some PCs have keener senses or professional training (elves, rangers) that reduces the chance of being surprised to 1 in 6, or cancels the training advantage of the opponent.
- A complementary skill check (Move Silently or Hide in Shadows, depending on context) can increase the chance of success by 2 in 6.
This fits neatly into the ability check system discussed above. The complementary skill roll is an interesting mechanic—it gives thieves a big advantage on some occasions, but prevents them from consistently surprising an opponent for several segments simply due to high dexterity.
We can propose an analogous
Bluff mechanic between (active) bluffing, taunting, and fast-talk and (passive) insight for NPC-PC interactions. The difference between bluffing and the reaction roll is that the former incites the NPC to take a short-term action, while the latter determines their general attitude towards the player or the party. Typically the reaction roll is only used when the group is trying to establish a relationship.
- The base chance of being believed or influencing the NPC significantly is 1-2 in 6.
- Individuals with a professional advantage (assassin, illusionist, bard) bluff on 1-3 in 6.
- Individuals that are naturally more insightful or familiar with bluffing techniques (assassin, illusionist, bard) reduce the chance to 1 in 6 or cancel the bluffer’s advantage.
- A complementary skill check (Persuasion, a new skill) can increase the chance by 2 in 6.
As with surprise, the result on the die indicates the number of segments that the target is convinced, distracted, etc. In combat time, this may be enough to cover an escape, to push past a guard post, to influence an attacker’s choice of targets, etc. However, a successful Persuasion check also increases the time that the target is influenced from seconds to minutes or turns, depending on circumstances. If the argument is inherently reasonable it can even permanently change the target’s attitude.
This mechanic can be used for other opposed checks.