The Planar Vagabond's Guide to the Multiverse

Heroic Old-School Roleplaying
Core Rules: The Basics

The HOSR system is designed to emulate the fun and fantasy of the classic “Basic” and “Expert” editions of the world’s most famous roleplaying system, without getting bogged down by an excess of rules. Most of it was built in layers over hundreds of hours of play, combining the best bits from over a dozen different systems.

These rules are still a Work-in-Progress, so if there’s some rule or feature you need that isn’t here yet, feel free to use the equivalent rule from your favorite B/X-compatible retroclone (we recommend Old School Essentials).

How to Play

There is one game-master (or GM). Everyone else is a player.

Each player controls a character (a player-character, or PC). All of the PCs together make up the party.

The GM’s job is to describe what’s happening in the game, and the players describe how their characters respond.

Sometimes, dice are rolled. These dice are described by how many sides they have (d4, d6, d8, d10, d12, d20, and d100).

Doing Things

Simple tasks are assumed to succeed. If the task is dangerous or complicated, roll the dice for an Ability Check.

For most checks, roll a 20-sided die (d20), add any modifiers, and compare the result with this table:

Advantage and Disadvantage

• Rolling with Advantage means to roll 2 dice and keep the highest result.
• Rolling with Disadvantage means to roll 2 dice and keep the lowest result.

Abilities

Each PC has 6 abilities that help to define how they can interact with the world. Each ability has a score from 3 to 18 (to start), and each score determines the modifier used when rolling a check for that ability.

• Strength (STR): Raw physical power, affects melee damage and carrying capacity.
• Dexterity (DEX): Speed and agility of movement, affects armor class (AC) when under attack.
• Constitution (CON): Mettle and gumption, affects hit points (HP) gained at each level.
• Intelligence (INT): Knowledge and reasoning, affects languages known and arcane magic.
• Wisdom (WIS): Experience and insight, affects divine magic.
• Charisma (CHA): Appearance and social capability, affects NPC reactions and eldritch magic.

Race, Class, and Level

Each PC has a race and levels in one or more classes.

• A PC’s race may influence their ability scores, and usually grants the PC one (or more) special features.
• A PC’s class determines what kind of weapons and armor they can use, how much damage they can take, and what special skills they have access to (including spellcasting).
  • As a PC gains new levels in a class, they may gain additional special features.
  • Some PCs can also multiclass, gaining levels in multiple different classes.

Saving Throws

When something (bad) happens to a character or monster, they can usually make a saving throw to avoid some (or all) of it.

• To make one, roll 1d20, add any appropriate modifiers, and compare the result with the Save value for your class and level.
• Some types of saves are harder, and have different modifiers:
  • Save vs Wielded rolls (avoiding wands, ray guns, or similar) get -1.
  • Save vs Blasts rolls (avoiding explosions, breath weapons, or the like) get -3.
  • Save vs Spells rolls (avoiding direct, targeted magic) get -4.
  • Save vs Paralyze is generally equivalent to a standard Save, and is mostly only kept for historical purposes.

Alignment

There are three alignments, cosmic principles that represent broad world views:

• Law: Order, truth, justice, and civilization. Typically prosocial.
• Chaos: Anarchy, power, chance, and entropy. Typically pro-individual.
• Neutrality: Balance, mediation, and detachment.

Some players also prefer to identify their character’s alignment along an additional (optional) axis:

• Good: Altruism and a respect for sentient beings, even to the point of self-sacrifice.
• Evil: Selfishness and lack of compassion for others, possibly even to the point of harming, oppressing, and/or killing them.
• Neutral: Have no interest in harming innocents, but are typically unwilling to make sacrifices to help a stranger (although they might for a close friend).

In general, evil characters are not allowed without prior GM approval.

Movement

Most characters have a base speed of 40’, indicating they can move 40’ in a combat round.

• Dungeon Turn: Can move 5x base speed (200’) in a turn (10 minutes) while exploring a dungeon.

Character Creation

1. Roll Ability Scores.
   • Roll 4d6 and keep the highest 3 (aka “4d6KH3”) for each ability.
   • Either roll 4d6KH3 once for each ability in order and see what kind of character comes up, or make all 6 rolls and assign the results to fit a particular class or concept.
   • On Roll20, all 6 scores can be rolled at once with this command:

/roll [[4d6kh3]] [[4d6kh3]] [[4d6kh3]] [[4d6kh3]] [[4d6kh3]] [[4d6kh3]]

2. Determine starting Race and Class(es) (even when playing as a human).
3. Determine starting level (ask the GM).
4. Note any special features the character has based on class, race, and level, including class skills.
5. Roll Hit Dice to determine maximum Hit Points.
   • Hit die type is determined by class, number of dice is determined by level.
   • Optionally, re-roll any 1s or 2s (once).
     • On Roll20, this can be done with /roll [[XdYr<3]], where X is your level, and Y is your Hit Die type.
   • For each die, modify the rolled value by CON modifier.
6. Choose Alignment.
7. Note starting Languages.
8. Determine starting Money.
   • For level 3 and under, begin with 3d6 x 10gp.
   • For level 4+, begin with Xd6 x 10gp, where X is starting level.
9. Buy starting Equipment.
10. Determine Attacks and AC.

Legal Information

This work includes material taken from the System Reference Document v5.1 (“SRD 5.1”) and/or v5.2.1 (“SRD 5.2.1”) by Wizards of the Coast LLC and available at https://www.dndbeyond.com/srd. SRD 5.1 and SRD 5.2.1 are both licensed under the Creative Commons Attribution 4.0 International License available at https://creativecommons.org/licenses/by/4.0/legalcode.