Old-School Essentials Classic Fantasy Rules Tome
Abstract
Old-School Essentials Classic Fantasy Rules Tome is a complete fantasy adventure game by Gavin Norman (Necrotic Gnome, v1.4). It is a faithful and finely reorganized restatement of the 1981 Basic/Expert ruleset (Moldvay/Cook), structured for maximum usability at the table. The book contains everything needed for years of play: character creation, seven classes, spells, monsters, treasures, and comprehensive referee guidance. It is the definitive mechanical proxy for the B/X tradition and is used here as the B/X baseline for system comparisons.
Character Creation
Stats: Roll 3d6 in order for six ability scores — Strength (STR), Intelligence (INT), Wisdom (WIS), Dexterity (DEX), Constitution (CON), Charisma (CHA). Score-band modifiers range from −3 (score 3) to +3 (score 18). Optional: swap STR/INT/WIS to raise a prime requisite up to +2, with no score lowered below 9.
Starting wealth: 3d6 × 10 gold pieces.
Alignment: Law, Neutrality, or Chaos.
Languages: Common + alignment language; INT-based additional languages.
Classes
Seven classes. Demihumans are race-as-class (no separate race/class split):
| Class | HD | Prime Req | Notes |
|---|---|---|---|
| Cleric | d6 | WIS | Spell slots 2–5, Turn Undead, restricted weapons |
| Dwarf | d8 | STR | Stonework detection, infravision, saving throw bonus |
| Elf | d6 | STR+INT | Spell slots 2–5 + fighter abilities, infravision |
| Fighter | d8 | STR | Broadest weapon/armor access; best THAC0 |
| Halfling | d6 | STR+DEX | Initiative bonus, hiding bonus, saving throw bonus |
| Magic-User | d4 | INT | Spell slots 2–6, broadest spell list, minimal armor |
| Thief | d4 | DEX | Thief skills (backstab, climb, sneak, pick locks, etc.) |
Prime requisite XP modifiers: ±5/10/20% for scores 3–8/9–12/13–18.
Advancement
XP thresholds vary by class. Fighters advance fastest; Magic-Users require the most XP. Maximum level is typically 10–14 by class. THAC0 improves per level bracket (roughly every 2 levels). HP gained each level by rolling class HD + CON modifier.
Core Resolution
Combat: d20 roll vs. the attack matrix (THAC0-based lookup). Lower THAC0 = better chance to hit. Descending AC (AC 9 = unarmored; lower = better). Optional ascending AC: AC 10 = unarmored, higher = better; use attack bonus instead of THAC0 matrix.
Modifiers: STR to melee attack and damage; DEX to ranged attack only. 1 always misses, 20 always hits.
Saving throws: Five categories per class/level — Death (or Poison), Wands, Paralysis (or Petrification), Breath Attacks, Spells (or Rods/Staves). Roll d20 equal to or greater than the target number to succeed.
Ability checks: Not formally defined in B/X. Referee uses 1-in-6 or 2-in-6 rolls for common uncertain outcomes (searching, listening, forcing doors).
Combat Sequence
Group initiative: each side rolls 1d6 each round. Winning side acts first in this order: 1. Declare spells and melee movement intentions 2. Monster morale (if applicable) 3. Movement 4. Missile attacks 5. Spell casting 6. Melee attacks
Optional individual initiative: DEX modifier applied to 1d6 roll.
Morale: 2d6 vs. morale score (2–12). Check when first death on a side or side reduced to half. Score 2 = never fights; score 12 = never checks morale.
Monster reactions: 2d6 table (2=hostile/attacks through 12=friendly/helpful), modified by PC Charisma.
Magic
Preparation model (Vancian): Spells must be memorized each day. Spell slots per level by class. Memorizing a spell expends a slot; casting expends the memorized instance.
Cleric spell slots: Levels 1–5; access from clerical spell list; no spell book required; divine selection by deity.
Magic-User spell slots: Levels 1–6; requires spell book; begins with 1 spell.
Elf spell slots: Levels 1–5 (as Magic-User, same list); in addition to fighter combat abilities.
Cleric Turn Undead: 2d6 roll vs. HD of undead; success drives or destroys undead. Effectiveness by cleric level and undead HD.
Spell disruption: If spellcaster is hit during casting or fails a save, the spell is lost.
Logistics and Encumbrance
Coin-weight system: items measured in coins (1 coin ≈ 10g). Movement rate reduced in tiers based on carried weight. Default unloaded speed: 120'/turn exploration, 40'/turn in encounter. Fully loaded threshold varies by carrying capacity. Strong characters can carry more without penalty.
Time tracking: 1 turn = 10 minutes (exploration). 1 round = 10 seconds (combat). Rest required 1 turn per hour; penalty: −1 to attacks and damage if omitted.
Equipment
Weapons: Full stat table with cost (gp), damage, encumbrance (coins). Melee and missile weapon sets. Optional rule: 1d6 damage for all weapons (simplification).
Armor: Plate mail (AC 2), chain mail (AC 4), leather (AC 7), shield (−1 AC). Costs range from 5 gp (leather) to 60 gp (plate).
Retainers: NPCs hired by PCs. Limit by CHA score. Require share of treasure (typically half-share). Loyalty check 2d6 vs. loyalty rating.
Hired specialists: Armorer, engineer, mercenaries, sage, ship captain, spy, etc. with listed costs.
Strongholds: Characters reaching name level (typically 9–11) can build a stronghold and attract followers.
Monsters
Over 200 monsters, each with: AC, HD, THAC0 equivalent, attacks, saving throws, movement, morale, alignment, XP, and treasure type. Treasure types A–V cover all monster hoards. Encounter tables: dungeon (9 levels), wilderness (by terrain type).
Magic Items
Over 150 magic items across categories: Armor and Shields, Miscellaneous Items, Potions, Rings, Rods/Staves/Wands, Scrolls, Swords (with sentience rules), Weapons. Each with full description and game effects.
OSE-Specific Additions vs. Core B/X
OSE is extremely faithful to the Moldvay/Cook B/X chassis. Additions clearly labeled as optional rules: - Ascending AC (optional rule): alternative THAC0-free attack resolution. - Individual initiative (optional rule): DEX modifier to d6 initiative per character. - Re-roll 1s and 2s (optional rule): for 1st-level HP. - High-Level Play (optional rule): guidance for levels beyond the Basic/Expert cap. - Domain Management: more explicit guidance for stronghold play. - Better cross-referencing and modular organization throughout.
Named Tables and Locators
| Table | Locator |
|---|---|
| Ability score modifier tables (STR/INT/WIS/DEX/CON/CHA) | Ability Scores section |
| Prime Requisite XP modifier table | Advancement section |
| Attack matrix (THAC0 vs. AC lookup) | Combat section, p.135 |
| Saving throw tables (by class and level) | Each class entry |
| Turn Undead table | Cleric class section |
| Thief skill progression table | Thief class section |
| Monster Reaction table (2d6) | Encounter section |
| Morale check procedure (2d6) | Morale optional rule section |
| Dungeon Encounter Tables (levels 1–9) | Encounter Tables section |
| Wilderness Encounter Tables (by terrain) | Wilderness section |
| Cleric spell lists (levels 1–5) | Cleric Spells section |
| Magic-User spell lists (levels 1–6) | Magic-User Spells section |
| Treasure Types (A–V) | Treasure section |
| Magic item tables (by category) | Magic Items section |
| Retainer Hiring Reaction table (2d6) | Hired Help section |
| Equipment price lists (weapons, armor, gear) | Equipment section |
See Also
- Retainer and Hireling Command Loop - Player-facing entourage management procedure based on OSE hiring and loyalty chassis
- Stronghold Lifecycle and Upkeep Cadence - Name-level holding maintenance and pressure cadence synthesized from OSE and domain-play sources
- Rival Adventuring Parties as Dynamic Pressure - Competing expedition procedure using reaction and morale behavior logic
- Kit-based Character Loadouts - Bundle-first alternative to open-market startup shopping
- Reaction and Morale Procedures - Cross-system comparison of first-contact and break-point behavior procedures
- Foundational RPG Comparison Scaffold
- Shadowdark RPG
- B/X Quick Start Rules
- Combat Sequence OSE SRD
- Encounter Sequence OSE SRD
- The OD&D Engine
Sources
- https://necroticgnome.com/products/old-school-essentials-rules-tome