B/X Dungeons & Dragons is a roleplaying adventure game of dungeon crawling and wilderness exploration.

Planning an Adventure

Before play can begin, an adventure must be planned. In the beginning, the referee will plan where the party goes and what they do. But as the party becomes more experienced, they will plot their own course, choosing where to go, what their goals will be once they get there, and what supplies they will bring on their journey.

The Dungeon

The dungeon exists in the mythic underworld. It is an otherworldly place that follows its own rules. You can’t expect everything to work as it does in the overland. Doors close on their own, passages and rooms shift from visit to visit, and it seems almost hostile to those visiting it. When exploring this malevolent domain, tread lightly.

Marching Order

Before descending into the dungeon, it is important for the party to establish a standard marching order. Who goes first, who goes last, and who’s in the middle? Single-file or side-by-side?

Mapping

At least one member of the party should be mapping the dungeon as you go. This doesn’t have to be overly detailed or complex. A simple flow chart will usually suffice—one you can follow when you’re making your escape.

Note Taking

At least one member of the party should take notes. These notes don’t have to be anything fancy—just simple reminders will usually suffice. What was that riddle again, what was the name of the bandit king, and where did we learn the key to the second level was located?

The Wilderness

The wilderness is wild and untamed. It is a magical place were the borders between the mortal world and the realm of Faërie are thin.

The Domain

The world is ruled by dukes and barons, powerful wizards and battle-hardened fighters. Someday, you may claim a domain and count yourself among their ranks.

The Basic Procedure

Play in D&D generally follows this basic procedure:

1. The referee describes the situation—what the characters see, hear, smell, taste, or feel.

2. The players may ask clarifying questions, to which the referee will further describe the situation, or the referee will indicate what action must be taken to acquire said information.

3. Based on the presented information about the situation, the players declare what actions their characters will take.

4. The referee and players resolve all such actions.

5. The above steps are repeated.

Turns and Rounds

Play proceeds in turns and rounds, each of which is just a variation of the above basic procedure.

The Turns

Downtime Turn

Downtime is when characters can accomplish things around town. Each real-world week counts as one in-game week—a downtime turn.

1. Each character in the party declares what downtime actions they will perform.

2. The referee details any dice to be rolled for success and how many downtime turns the declared actions will take. The party rolls any appropriate dice, and the referee describes the results of their downtime actions.

3. The referee updates time records, paying special attention to the effects the party’s downtime actions have on the world.

Wilderness Turn

When exploring the wilderness, time is tracked in wilderness turns. A wilderness turn lasts about four hours and uses the following procedure:

1. The party decides on a course of action—moving into an adjacent hex, performing a task in the current hex, et cetera.

2. The referee rolls for weather, losing direction, and random encounters.

3. The Referee describes what the party sees as they travel and asks the party what they do, switching to the dungeon turn or encounter turn (or combat round) as required.

4. The referee updates time records, paying special attention to supplies, spell durations, and the party’s need to rest.

Dungeon Turn

When exploring the dungeon, time is tracked in turns. A turn lasts about ten minutes and proceeds thusly:

1. The referee rolls for wandering monsters.

2. The party decides what they want to do—moving, entering rooms, listening, or searching—and the referee describes what the party sees and what happens. (If monsters are encountered, the encounter turn is used.)

3. The referee updates time records, paying special attention to light sources, spell durations, and the party’s need to rest.

Encounter Turn

When a monster or NPC (non-player character) is encountered, play switches to the encounter turn.

1. The referee rolls for surprise and reaction, if applicable.

2. The referee determines how far away the monsters are from the players’ characters.

3. Sides that are not surprised roll initiative to determine who acts first.

4. Sides that are not surprised decide how they will respond to the encounter (such as by fighting, running, talking, or waiting). The encounter is played out accordingly.

The Round

When an encounter becomes combat, time is tracked in rounds. A round lasts about ten seconds and proceeds thusly:

1. Each side declares if they’ll be casting any spells or moving while in melee combat.

2. Each side rolls 1d6 for initiative.

3. The winning side acts:

   1. Morale is checked (for retainers or monsters).

   2. Movements are made.

   3. Missile (ranged) attacks are made.

   4. Spells are cast.

   5. Melee attacks are made.

4. The losing sides act.

The Dice

The game uses funny dice with many sides. The notation for these dice is ydx, where y represents the number of dice and x represents the number of sides. For example, roll 2d6 means to roll two six-sided dice (the regular-looking ones).

Z-in-X

For a z-in-x roll, you must roll a dice with x number of sides and get z or lower to succeed. This kind of roll is most often used for skills. For example, a Dwarf looking for secret doors might have a 2-in-6 chance of finding one. The player would roll 1d6 and succeed on a roll of 1 or 2.

Remember: You want to roll low on this kind of roll.

Ability Check

When rolling an ability check, roll 1d20. You succeed by rolling your ability score or lower. For example, our Dwarf has to make a Strength ability check. His Strength score is 13, so he must roll a 13 or lower on 1d20 to succeed.

Remember: You succeed when you roll within (roll under or equal) your ability.

Saving Throw

Saving throws are 1d20 rolls. You succeed by rolling your appropriate saving throw score or higher. For example, our Dwarf has a Breath Attack score of 13, so he must roll a 13 or higher to succeed on his saving throw.

Remember: You succeed when you overcome (roll over or equal) your saving throw.

Attack

An attack is a 1d20 roll to hit a target. You succeed by rolling, adding your appropriate ability modifier, equal to or over your THAC0 (to hit armor class 0 from your attack matrix) minus the target’s Armor Class (or AC). For example, our Dwarf with a THAC0 of 19 attacks a Goblin with an AC of 6, which means he must roll a 13 or higher to hit. He is attacking with a mace, which is a melee weapon, meaning he can add his Strength modifier of +1 to his roll.

Remember: You want to roll high on this kind of roll.

Damage

After you’ve successfully attacked, roll the damage dice indicated by your weapon. The result of your roll is how much HP you subtract from your target. In our example above, the Dwarf rolls 1d6 for his mace (once again adding his Strength modifier of +1).

Remember: You want to roll high on this kind of roll.

When to Roll

Rolling the dice is a failure state. Whenever possible, you should try to stack the deck in your favor and attempt to avoid having to roll.

Z-in-x rolls are usually skill checks and are made whenever attempting a relevant task and there is risk involved in failure. Some risks include time lost, tools expended, et cetera.

Ability checks are rolled whenever attempting a relevant task that isn't covered by a skill where there is risk involved in failure. Given appropriate time and tools, no roll is usually needed.

Saving throws are rolled whenever required by the rules and situation.

Attacks and damage are rolled when in combat.

“Winning”

While the ideas of “winning” and “losing” are important in many games, they don’t really apply to Dungeons & Dragons. Sure, you could think of gaining treasure and leveling up as winning, or of your character dying in the dungeon as losing, but neither of those things end the game. When you complete a dungeon and gain enough treasure to level up, there are always new challenges to face. Conversely, when tragedy strikes and your character dies in the dungeon, you can always create a new one. The game never has to end.

You might be tempted to think there are two sides in a game of D&D: the players versus the referee. That is not the case. The referee is simply attempting to play the world in a fair and balanced way. Sometimes, through the actions of the party, that results in gaining massive hoards of treasure. At other times, it may result in death. But in the end, everyone’s goal, both players and referee, is to have fun. We’re all on the same side.

Character Creation

Character creation follows the steps in the Old-School Essentials Classic Fantasy system reference document with the exceptions outlined in the B/X Character Creation document.