The following is a comparison of TSR-era D&D editions and/or their derivatives that is mostly intended for my own reference when considering different editions to run, or if I am considering pointing others towards a specific game I would like to run. If anyone reading this blog can point out corrections or additional information, feel free to comment.
Systems Considered:
S&W (Swords and Wizardry Complete, 2008, an OD&D (1974) Retroclone1)
B/X (Dungeons and Dragons Basic/Expert, Moldvay-Cook, 1981, consulting Old-School Essentials for clarifications. Additional references to Rules Cyclopedia)
AD&D (Advanced Dungeons & Dragons, 1st Ed., 1977, consulting OSRIC for clarifications.)
Characters
Character Classes:
S&W: Assassin, Cleric, Druid, Fighter, Magic-User, Monk, Paladin, Ranger, Thief
B/X: Cleric, Dwarf, Elf, Fighter, Halfling, Magic-User, Thief (See Rules Cyclopedia for Druid and Mystic.)
AD&D: Assassin (T), Bard (F/T), Cleric, Druid (C), Fighter, Illusionist (M), Magic-User, Monk, Paladin (F), Ranger (F), Thief
(Note: Parentheses indicate a sub-class. Bard and Monk excluded from OSRIC. Additional classes in Unearthed Arcana, such as Barbarian and Cavalier.)
Character Races:
S&W: Dwarf, Elf, Half-Elf, Halfling, Human
B/X: Race as Class.
AD&D: Dwarf, Elf, Gnome, Half-Elf, Halfling, Half-Orc, Human
Alignment:
S&W: 3-point Law-Neutral-Chaos
B/X: 3-point Law-Neutral-Chaos
AD&D: 9-point Good-Neutral-Evil and Law-Neutral-Chaos
Maximum Level:
S&W: 20
B/X: 14 (see Rules Cyclopedia for up to 36)
AD&D: 20
Gygax suggests training required at a rate of current level × 1,500gp per week in order to gain levels.
Spell Lists and Max Spell Levels:
S&W: Cleric (7), Druid (7), Magic-User (9)
B/X: Cleric (5), Magic-User (6)
AD&D: Cleric (7), Druid (7), Magic-User (9), Illusionist (7)
S&W: Can be transcribed to spellbooks. Must Read Magic for arcane scrolls first.
B/X: Can only be cast. Must Read Magic for arcane scrolls first.
AD&D: Can be transcribed to spellbooks. Must Read Magic for arcane scrolls first.
Adventures
Timekeeping:
S&W: 10-minute Turn, 1-minute Round.
B/X: 10-Minute Turn, 10-second Round.
AD&D: 10-Minute Turn, 1-minute Round, 6-second Segments (10/Round)
Movement:
S&W: Movement rate e.g., 12. (×20 = feet/turn; ×10/3 = feet/round in combat)
B/X: Base movement (Encounter movement) e.g., 120' (40')
AD&D: Movement rate e.g., 12". (Conversions: 1":10' per turn of exploration or combat round. 1":1' per combat segment. 1":2 miles per day of travel.)
Encumbrance:
S&W: Weight measured in pounds. Affects movement only.
B/X: Weight measured in coins. Affects movement only.
AD&D: Weight measured in pounds. Affects Surprise and Initiative
Random Encounters:
S&W: 1-in-6 chance every turn, but suggested as few as every 3 turns. Variable dungeon level. d6×10' distance in dungeon. (×3 to ×10 in wilderness.)
B/X: 1-in-6 chance every 2 turns. Standard dungeon level. 2d6×10' distance in dungeon.
AD&D: 1-in-6 chance every 3 turns. Variable dungeon level. d6+4" distance in dungeon. (50' to 100') Base 6d4" distance in wilderness, modified by surprise.
Reaction Rolls:
S&W: 2d6. Low rolls are hostile.
B/X: 2d6, modified by Charisma of interacting character. Low rolls are hostile.
AD&D: d%. Low rolls are hostile.
Combat
Operation Order:
S&W: 1. Declare spells; 2. Initiative; 3.Movement and Missiles, then losers of initiative; 4. Spells and melee, then losers of initiative.
B/X: 1. Declare spells and melee movement; 2. Initiative; 3: In order: Movement, Missiles, Spells, Melee. 4: Opposition.
AD&D: 1. Declare intentions including spells; 2. Initiative; 3: Resolve in initiative order.
Surprise:
S&W: d6. 1-2 is surprised for one round, but only 1 if Monk or Ranger in party. 1-in-4 chance of dropping a held item if surprised.
B/X: d6. 1-2 is surprised for one round.
AD&D: d6. 1-2 is surprised for that many segments. Dexterity modifiers can negate these segments for individual characters.
Initiative:
S&W: Group d6, highest goes first. Ties are either simultaneous or re-rolled per DM choice.
B/X: Group d6, highest goes first. Ties are either simultaneous or re-rolled per DM choice.
AD&D: Group d6, highest goes first. Each side acts on the other die’s segment. Ties are simultaneous. Spells resolve at appropriate segment per casting time.
Move and attack:
S&W: Can be combined.10' melee range
B/X: Can be combined. 5' melee range.
AD&D: No melee until after the round distance is closed, unless charging (×2 move). Defender can set to receive charge.
Back Stab (Thief):
S&W: +4 to hit from behind for Thieves and Assassins. If also surprised, damage multiplied based on level.
B/X: +4 to hit if unaware and from behind. Damage doubled.
AD&D: +2 to hit from behind (or +4 if also with surprise), damage multiplied based on level.
Attacks of Opportunity/Fleeing:
S&W: Free attack as the character moved out of 10’ melee range, made at +2. Optional.
B/X: +2 to attack from behind; No automatic attack.
AD&D: Free attack(s) at +4 (i.e., treat as stunned)
Missile attacks:
S&W: +0 at short range, -2 at long range.
B/X: +1 at short range, +0 at medium range, -1 at long range.
AD&D: +0 at short range, -2 at medium range, -5 at long range.
Firing into Melee:
S&W: Random.
B/X: No mention.
AD&D: Random. Adjust probabilities based on sizes.
Monster Morale:
S&W: Mentioned in the abstract.
B/X: 2d6 vs. Monster's score. Equal or lower continues to fight. 2 successes will fight to the death. Optional.
AD&D: d% roll for resolve; Base 50%, +5/HD >1, +1/extra HP. Additional situational modifiers.
Pursuit:
S&W: No mention.
B/X: Monster reaction roll. Success based on movement rate.
AD&D: d% roll for pursuit chance. Depends on intelligence and situation.
AD&D Note (Spells and Weapon Speed):
If lost initiative but attacking spellcaster in melee, subtract losing initiative die roll from weapon speed. If the result is less than the casting time, an interrupting hit is possible.
In tied initiative, If the slower weapon has a greater speed factor by either +5 or 2x, the faster weapon gets 2 attacks before slower. If the difference is 10, the faster weapon gets a 3rd attack simultaneously with the slower weapon attack.
There is a table for bonuses and penalties to hit based on different armor types. Thus, certain weapons are better for lightly armored foes, and others for heavily armored foes.
As stated before, please feel free to comment below to point out inaccuracies or important omissions. In a future blog post, I hope to compare stat monster block formats found in adventures for various rules systems, as well as looking at how a monster changes across those rules systems as well.
1 - Note that of the three systems compared, I consider Swords and Wizardry to be probably the most removed from its inspirational edition of D&D, so I don't want to simply call it OD&D. (For example, the default option is a single saving throw, as opposed to the 5 different types.) As far as I know, it is an interpretation of the rules comprising Chainmail, the original D&D Box set, all supplemental booklets, and some articles from The Strategic Review. There are also the White Box (Original 3 Booklets) and Core (Same, with Greyhawk supplement) editions of S&W, but I imagine they are mostly stripped-down versions of S&W Complete. In reading the Swords and Wizardry Complete rulebook, however, there are well-presented notes about changes from the original rules.
