Overview
These are my OSE house rules that I've developed over the last few years. My general philosophy is to change as little as possible to the original BX rules, while making them clearer. Most of these came up in actual play, and we wrote down the resolution as a house rule. All page numbers are referenced to the Advanced Fantasy Player's Tome.
Advanced Optional Rules
- Character creation method will be the “Basic Method” on pg. 16
- All combat rules on pg. 224/5 except “Missile Attacks on Targets in Melee”
- “Secondary Skills” on pg. 25
- “Casters and Staves” for casting classes
- “Limits on turning the undead” on pg. 111
- “Advanced Spell Book Rules” on pg. 112
- “Basic Encumbrance” on pg. 203
Combat
- Generally we’ll use the optional individual initiative rules for combat
- Some more complex combats will use the group initiative rules
- In each round of combat a character can move and take one action, in any order
- This action can be attacking, drinking a potion, casting a spell, shooting a bow, grappling an opponent, etc.
- Critical hits do double damage, fumbles fight last next round
Skill Checks
- All characters can sneak, climb, etc, with an ability check
- If an ability check is opposed, roll as normal with a penalty equal to the opponent’s attack bonus
- Thief-like skills are preternatural abilities that are rolled to avoid an ability check
- e.g. when sneaking the thief can roll their percentile “move silently” check to sneak past an opponent
- if they fail they roll an opposed DEX ability check as normal
Arcane Casters
- Learning a found spell takes one night, with a chance of failure as per the advanced spellbook rules
- If the attempt fails, the caster can’t learn the spell from that source, but could try again from a different source
- Any spells can be learned via the “creating new spells” magical research rules, including ones that already exist in the game’s spell lists
Rations
- Rations last for 7 days before going rancid, whereas iron rations last forever
- Edible monsters can be butchered into 1d6 rations per hit die
Experience Points
- The DM will award XP at the end of every session for treasure recovered, monsters defeated, and carousing
- Monsters and treasure XP are as per the normal rules, except all characters get the full amount of XP earned
- Carousing is awarded for spending gold on non-adventuring activities (e.g. building a temple, throwing a massive party, erecting a statue in your own honor, etc.)
Magic Items
- Magic items that require activation, and don’t have a persistent effect, can be activated with an action
- Magic item use can’t be interrupted in the way that spells can, and their use doesn’t need to be declared before rolling initiative
Death
- When a character has 0 hp or less, they roll a death save
- If they pass, reset their hp to 1
- If they fail, they die