OD&D in B/X

I like OD&D flavor more than B/X flavor, but I’ve been running games from OSE because it’s just easier to do that. The books are easily-referenced, easy to understand, and there’s a humongous stack of material designed for B/X or instantly convertible.

So, I’m thinking about implementing as much OD&D as I can manage by a short house rules document. What would that look like?

A quick glance through this Smoldering Wizard blog post gave me a list to consider.

The Many Unique Rules of OD&D

• 3d6 in order is the only option.
• Hit points are rerolled at each level.
• There are no strength bonuses.
• Dexterity gives only a +-1 bonus or penalty to missile weapon to-hit rolls. (No AC bonus from DEX.)
• All weapons do 1d6 damage.
• Magic-Users and Clerics must carry one spell book for each level of spell they know.
• Clerics must choose to be either Lawful or Chaotic by 7th level.
• Cure light wounds requires a full exploration turn.
• Monsters are worth 100XP per hit die. This is limited by the ratio of monster and dungeon level (defeating an orc on the 5th dungeon level gives only 1/5 experience.)
• Players may designate a relative to inherit their possessions should they die.
• Monsters and Fighting-Men gain one attack per round against normal men for each of their own hit dice. Attack bonuses apply to only one such attack.
• All magic swords have an alignment, touching a sword of a differing alignment causes the player to take damage.
• All magic swords are intelligent, but 50% of these have enough intelligence to possess an ego and one or more special powers. They might guide or even control the sword owner.
• 10% of all magic swords will have a special purpose (example: slaying a specific kind of chaotic creature.)
• Scrolls are for Magic-Users only, except that protection scrolls can be used by any player. 25% of scrolls found will have cleric spells.
• There is a 25% chance a surprised player will drop a held item.
• All monsters can see in the dark, but no player character can. Monsters serving a player lose this sight.
• Most dungeon doors are difficult to open for players and doors always close on their own, but monsters open them immediately.
• There is a 2-in-6 chance that doors spiked open by players will close due to the spikes slipping.
• Only 1st level characters can be hired as retainers
• Retainers have a secret 3d6 Loyalty score
• No roll to see it they leave service at the end of the adventure
• no XP halving for retainers
• no need to memorize spells for magic users. You have access to all spells of levels you can cast, you can cast per adventure as many of each level as indicated, but only once each. No memorizing

Philotomy’s House rules

• To adapt BX monsters: If the monster does d4 or d8 damage, you may change their damage die to a d6-1 or d6+1. If they do d10 or more, drop the decrease the die by 1. (A d10 would become a d8.)
• Advantageous weaponry, terrain, or maneuvering, may result in a to-hit roll gaining advantage (roll 2d20 when attempting to hit an enemy and keep the better result) or a bonus (such as +1) as the referee deems appropriate.
• The referee may sometimes grant initiative without calling for a roll based on what weapon is used and how it is used.
• An additional damage die may be added to the roll if the ideal weapon was used against an enemy type (for example, using a blunt weapon vs. a skeleton.)

Further thoughts

• Fighter only: Two-handed weapons roll damage twice and take the higher result.